I can't think of a reason not to do it
I've mentioned a couple above but here is one:
it might stop you flying altogether.
I have a limited flying budget, I don't want to spend that following a magenta line or flying in cloud. The appeal of flying, for me, is seeing the world from above. If I had to spend a decent proportion of my budget on keeping current at something that doesn't interest me and I don't want to do, then I'd give up. As, I suspect, would many microlighters, permit flyers etc. We are seeing pilots hanging up their headsets more and more, don't do something that puts you closer to doing that
If you are going to use an IMCr or IR then get it. If you are going to need it, get it. If you are going to enjoy the process of getting it, go and get it, but if you are a fair-weather, Sunday afternoon flyer who doesn't want to spend valuable flying time head in the cockpit, then be realistic about the positives and negatives