Now, I played a lot of Nethack (back when it didn't have tiles), Angband (both when it was still Moria, and later), and the like, so I'm not bothered by ASCII - and, as someone pointed out, a D can be as scary as it gets (only, be careful when switching roguelikes - and "d" changes from representing your puppy to a young dragon).
But then, there's the question of screen readability. When playing, I don't recognise the difference on-screen between a workshop and another workshop - so, since I'm still discovering the game and not planning my fortress layout too well, I'm always lost when I need to find a specific workshop. Using more customized characters could make the screen much more readable.
Now, for what is "needed", or even what "we the players" can build - DF is made, for their own reasons, by two people. Nothing is "needed" but what they want to put in it. And since they decided not to release it as free software - their completely legitimate decision, even though I'm have made a different one if I had one percent of their talent and dedication, which I don't - there isn't much that one can do to "help". Wesnoth works differently, and tries to appeal to a different crowd (I happen to sit in both, but again, that means nothing), under a completely different development model. Apples and oranges...