They design buildings as if they don't use their brain.

They don't know how to manage space.

I am not an architect, but I can rest assure you that using my common sense I can design buildings and interiors that surpasses what most Nigerian-trained architects can design.

They design the interiors of residential homes without walk-in closets, without any sense of saving space, and without any open feel to it.

They design residential buildings as though they are designing prison yards, for instance, designing a wall to block a kitchen from the living room, and another wall to block the dining room from the living room. Such unnecessary walls makes the interior of the house look like a prison that is meant to separate the occupants, and it is an added expense for the client.

Their designs are so simplistic that any man with common sense can create such designs. So what do they learn in Nigerian architecture schools.

I can go on and on, but you get the gist.

You are so right. Imagine separating bathroom from toilet. Imagine dining room with a door. Imagine separating madam room and Oga patapata room with a door in the middle of both rooms instead of a master suite for husband and wife. Imagine a kitchen with a just one small window. Imagine painting every room in a house with different colors, for examples; 4 bedrooms, 2 bathrooms, 1 kitchen and 1 storage = 7 different colors or paint. Imagine a 3 bedroom bungalow with 10-15 concrete pillars and 6 inch german floor in a non swampy or sandy area. The list goes on and on.

Princek12: They design buildings as if they don't use their brain.

They don't know how to manage space.

I am not an architect, but I can rest assure you that using my common sense I can design buildings and interiors that surpasses what most Nigerian-trained architects can design.

They design the interiors of residential homes without walk-in closets, without any sense of saving space, and without any open feel to it.

They design residential buildings as though they are designing prison yards, for instance, designing a wall to block a kitchen from the living room, and another wall to block the dining room from the living room. Such unnecessary walls makes the interior of the house look like a prison that is meant to separate the occupants, and it is an added expense for the client.

Their designs are so simplistic that any man with common sense can create such designs. So what do they learn in Nigerian architecture schools.

I can go on and on, but you get the gist.

You might right about your observations. But you should also note that you cant group everyone in Nigeria as corrupt because a policeman collected 100 naira from you.
That ''nigerian architects are so incompetent generalisation is false''
As an architect, i have made so many mistakes in my designs for clients. Now some mistakes coming from ''not verifying the nature of the land'', and others from not seeking the consent of the client,(believing you know their taste and mind)
I have cause to believe that you are posting from experience, both from maybe having being rendered a bad service by a designer and also living in homes outside Nigeria. Sorry for the former(if it is true). For the latter, these homes i assure you was not built with our ''insecurity'' mentality.
Firstly, all clients are not the same. Some consider security above functionality. Others consider privacy above aesthetics. Like you said about the kitchen opening to the lounge, thats your taste. Now, i offered such design to a client a while ago and he asked me ''so if my wife is cooking, the visitors in the lounge will be perceiving it?
I have also had clients who told me that they do not want an open feel between the dining and the lounge, that they want a door! Talk about ''walk in closet, not many clients like this either! Some think it has become monotonous.
The basics of a good design, i think should be ''if the designer was able to satisfy your brief to at least a 75% mark, not walk in closet, kitchen...etc.
What did you tell him to design for you? What was your brief to him? Did he achieve it?
In a designer-clients' relationship, the designer should endeavour to show the interior arrangement, modify it to the clients' taste, and if possible inform the client of any slightest change in the design. The client may also show it to any other designer for criticism. Most of the problems we face comes from duration of achieving and modifying a design. Some clients do not even bother to take their time and see if the design suits their taste. They just tell the designer to go on and produce the final working drawing. Now when they go to the site, they start complaining and start adjusting and pulling some walls down.

Mr Prince as long as I am concerned is less informed in what he feels he's observing. Culture and climate plays a very important roles in what he mentioned here. In Europe, you need the heat from the kitchen and dining is always close to the entrance because a guest could eat with you and leave without entering your great room. But here my brother, a visitor could poison your child eating in an open dining.
If you really have a home of your own, tell me... How many times have you or your family eaten on the dining with like four guest in your house watching you? The two cultures here make it difficult for you to keep to your meal time if you have guests because in Africa, we visit ourselves even without invitations.
If you really understand your environment very well, you should be able to know why some things happen the way they do.
Basically he explained to you here that client demands shouldn't be ruled out. If you need an open kitchen and dining, tell your architect to do that for you... For me, even as an architect, I prefer walling off of kitchens because in Europe it saves heating cost but here your spend on mechanical equipments to make it work.
Building it is not the issue, but running the maintenance cost bearing in mind that PHCN will always be two street away from you.
Bless you.