Hakagure:
First we must define the space we are talking about. Specifically here we are talking about the foreign exchange market.

The foreign exchange market is where all the worlds currencies are purchased and sold, it is the biggest finance market in the world, prices are set by demand and supply, in the event of a dollar peg (as opposed to a freely floating currency) the country pegged to the dollar ensures that it buys its currency at a fixed ratio compared to the dollar irregardless of demand and supply, this is known as defending the currency, other ways a currency can be defended is by using "currency controls". These include


Banning the use of foreign currency within the country
Banning locals from possessing foreign currency
Restricting currency exchange to government-approved exchangers
Fixed exchange rates
Restrictions on the amount of currency that may be imported or exported

I will now steal wholesale from Wikipedia to define how this "pegging " is done.

Open market trading

Typically, a government wanting to maintain a fixed exchange rate does so by either buying or selling its own currency on the open market. This is one reason governments maintain reserves of foreign currencies. If the exchange rate drifts too far below the fixed benchmark rate, the government buys its own currency in the market using its reserves. This places greater demand on the market and pushes up the price of the currency[citation needed]. If the exchange rate drifts too far above the desired rate, the government sells its own currency, and buys foreign currency, thus reducing the pressure on demand, and its foreign reserves fall.

Fiat

Another, less used means of maintaining a fixed exchange rate is by simply making it illegal to trade currency at any other rate. This is difficult to enforce and often leads to a black market in foreign currency. Nonetheless, some countries are highly successful at using this method due to government monopolies over all money conversion. This was the method employed by the Chinese government to maintain a currency peg or tightly banded float against the US dollar. Throughout the 1990s, China was highly successful at maintaining a currency peg using a government monopoly over all currency conversion between the yuan and other currencies.

As anticipated, Nigeria pegs its currency, defends it currency and controls its currency. keeping a fixed currency is an active process in which the nation makes it prohibitive for small buyers/sellers of foreign currency to "short" its currency or drive its currency lower, keep in mind that controlling currency is currently an exception and is not a rule, some countries actively keep their currency devalued (but we will get to that later, this is referred to as currency manipulation). One of the reasons the naira devalues is simply because the dollar got stronger, another reason is because our forex reserves are reducing as the price of Oil falls, you , I, Buhari nor the Saudis can control the price of Oil any more (OPEC did successfully for a long time but are being under cut by Shale)

These controls and pegging have the following effect on an economy.

Drives up cost of capital, discourages FDI. This disproportionately affects small companies.
We spend forex defending the naira ($3.4 just keeping it pegged as per BBC)
- http://www.bbc.com/news/business-33258942
Create a parallel market for people who want to import goods on the non approved list
Drive up prices of good on the market (effectively inflate the market for imported products)
Capital flight due to high cost of capital, so FDI leaves. Rightly capital anticipates taxation as the next move after currency controls (in order to control inflation) hence capital flees the country
Whats the extreme case: Lets imagine the pressure continues and CBN keeps defending the currency as capital flows out and balance of payments worses. Well, we dont print dollars (and thats what the CBN needs to use to defend the naira) so eventually, our forex gets so low there is a chance we do not make our debt payments, seeing this impending cliff event CBN will either stop propping up the dollar or stop making debt payments . If you stop making debt payments... well. Thats the nuclear option.

Once they stop propping up the naira, the naira crashes precipitously and the stock exchange with it (jobs go, companies fail) The exact same thing you tried to avoid happens all at once. The govt begs IMF or World Bank for a massive infusion of dollars (thats what we neeed, not naira which we can print willy nilly) and then in return IMF/ World Bank asks for higher taxes, austerity, privatization of everything in sight then kindly gives us a loan in return which we use to arrest the precipitous decline. Meanwhile we go through another period of Austerity.

The dark dark thing is this, this has happened before. Buhari refused to devalue in 82, Babangida came in and had NO CHOICE, plunged us into severe austerity (SAP). Same macro events (oil price tanked, Nigerias balance of payments skewed) led to same disastrous events (massive devaluation and privatization, failure of companies and the stock exchange and austerity). So your analysis is...over simplified and distorted.

I anticipate your response.