The developers could've worked harder on graphics instead of making letters and symbols, guaranteed. Tilesets aren't default, those are made by the community, and they are still ugly.
The game is difficult to master, I understand. Some people just can't stand the games where you have to think. I know, people making you think in a video game! The horror!
The developers didn't bother with better graphics because anyone who couldn't stand them probably wouldn't have enough intelligence to understand the game anyways. And because its s till in development.