15 Ahmadis arrested for gathering in a building resembling a mosque

You really do miss the point...

Laws should be obeyed, so long as they are reasonable. When laws are unreasonable and unjust, then people have a right to rebel.
By your logic, if tommorow the Pak govt were to say all Muslims should stop being Muslim, you would gladly oblige.

And the reason they make a building to resemble a mosque is because
a. They say they are Muslim, and refuse to be told otherwise.
b. Because archtecture is not copyrighted by Islam. A mosque can take any shape, be arabesque, moorish, or whatever. You might be interested to know that the early Islamic Archtecture was influenced by Byzantine Christian architecture... And there are even Churches and synagogues that look like Mosques!

So its pretty ridiculous no matter what angle you look at it.