No reason at all. There is no need to restrict yourself to clipless, in fact, apart from periodic experiments that only ever support my preferences, clipless aren't needed at all. You DO need good foot retention for fg but all you need are good toe clips and straps. I ride the MKS Urbans with toe clips and straps, set firm but loose enough to get into and out of, and that's all that's needed. Beyond that, you need to think very carefully about your technique to gain any benefit.

Go fg now my son. Fit platforms, toe clips and straps, you'll be fine and still able to wear your funny shoes. My only advice is to clean and oil your geared bike first because if you don't, when you finally remember the thing in a year's time, it'll be rusty