You are not being forced to do so, as FTS said, most popular maps on b.net are unprofessional looking, and professionalism does not mean more restraints, I think our ideas of professionalism is different, IMO all it comes down to is how the idea is presented, do you colorize your text, is terrain symmetrical, square or not, when necessary, or does it just look like you slapped it all together.
My idea of a truly professional looking map that is amazing is Rush, extremely professional looking, awesome map, tell me, how would that map have been any worse if it didn't have the professional looks about it?
Of course you're being forced to; look at the reception that's given to a map that doesn't have professionalism. That reception is a result of expectations created by maps with needless professionalism.
People have a limited amount of time and effort to spend on a map. Pushing up against those limits, especially if it's for an aspect of mapping that you don't enjoy, makes the process less fun and reduces the chances that the map will be finished.
Think about it this way: when earlier-generation UMS maps came out, did anyone look at the non-colored text, the use of isometric terrain for basic area sectioning, the slight asymmetries in the layout, and go "OMG newb map" and leave? No; they stayed, they played, and they
enjoyed the map. And if people would play those maps without judging them on the basis of professionalism, they could still enjoy them. But that enjoyment has been denied to them because they have been trained to judge maps on the basis of superficial, aesthetic factors. It's just like how "improved" graphics in commercial products have damaged indie gaming; but while commercial games are made for profit, which partially excuses, or at least explains, their self-centered approach, map-making is just something done as a form of play, and when playing, you have to be considerate to your companions, in this case, the greater SC community.
Or think about this: if colored text, for example, had never been discovered, never been used, would anyone care if maps didn't have it?
None.