Don't feel bad about your purchase. These tractors are very handy to have and will go in places that the bigger ones can't go.
I don't know about your uses, but for me, one of these smaller tractors would be great for tilling the ground as close as possible to the trees on the orchards, while the bigger tractor would handle the rest of the tilling. Same for mowing the brush or grass.
This is just a couple of examples, there are plenty uses for these small tractors, specially once you convert it to a Cat 1 hitch.
If you really can't find a use for it, I'm sure you can easily sell it for what you paid.