Yeah, sometimes it's easier to start over if your program has a bunch of no longer desirable features built in. I've played some very enjoyable dungeon crawlers that only had one wall texture, but you will probably want at least doors and wall switches as well. Since you no longer have the time crunch of a game jam, it may be better to focus on the game's basic systems first but leave yourself room to make it flashier later on.
My plan going forward is making a system that is easily modified. a way to create preset levels, an entity system that can be used for decorations/doors/creatures, a text box and menu system that is meant to be very flexible in it's use. Effectively I hope to make a dungeon crawler template that I and others can use without having them all have very similar gameplay. It's something I have to do a bit of planning ahead for, but once it's done it could be a good tool for anyone who wants to make a dungeon crawler on the gba, which admittedly is a pretty niche audience lol.