Personally, I think some new tile insertions are disgusting, if done overboard. I hate the trend of trying to make everything 3D, like the new games. I mean, new tiles are nice. New tiles, no one said wannabe three-dimensionals.
In my opinion, I think new tilesets improve a game's overall appearance. DEFINITELY not necessary, but it is a big benefit if used properly. I wish I knew the works of tile insertion and the like, but I don't. Basically, if you can't do it, you have three options: A) Move on without it, B) Put yourself through rigorous training in order to learn a new thing C) get someone else to do it.
I'd choose B, but I flat out don't know how to learn about it. So I'm most likely going to do C). To answer the poll, move on if you can't do it. You can try, but don't lose hair over it. It really isn't worth it. After all, scripting and relatively new maps can compensate for the lack of new tiles. Scripts (used for a good storyline) > Anything else, in my opinion.