Given how some churches have adapted to this COVID-19 situation and how services are being held online, offering are being collected online and almost everything else is done online, what then is the importance of the physical church? Why the large buildings, excessive 'religious props' etc?

If most Christian leaders believe that messages can be passed across online, miracles can happen online and so on, is it safe to say we can do without the "physical gathering of the brethren"?

Yes it is

seunlayi:
Yes it is

I hope you are not trying to mock, but I'd like to answer.

The sincere, true church is comprised of fellow believers.
There is power in the corporate gathering of people of like minds worshiping our Saviour in spirit and in truth.
Members gather (or at least are supposed to gather) for the purpose of encouragement, edification, admonition, support, fellowship, and to get re-energized to partake in the ministry of winning souls to Christ.
There is power in touch and communication.
That is something that cannot be gained by self-isolation and with non-believers.
So no, it isn't safe to say that the physical structure should be forever closed.

However, it is not necessary to build huge, extravagant buildings which foster pride. It is not okay to be obsessed with "prosperity" in its many forms either.
A simple building with a sturdy roof, working doors, a clean and safe inside area etc., is sufficient.

The church is Christ' bride. He died for it and will always see it as the apple of his eye.