I def agree with your sentiments and although this topic has been beaten to death,I often keep coming back to the same question, myself. Obviously it's a deeply personal question, and the answer is different for everyone. I think it boils down to the fact that I love a certain era of guitars and basses. Particularly designs from the 50s-70s. It's just fun to play and collect different guitars. I've reached a place in my life where I am fortunate enough to splurge once in a while on a nice instrument. As a result, I have accumulated quite a few over the years.
Is it excessive? Perhaps. Am I a pro gigging musician? Absolutely not. But having the option to plug in a wide variety of instruments when I get home from work in the evening gives me a nice feeling. I try to bond with all instruments I own on some level. Others are just case queens that I am proud to own and bust out every so often. Call it stupid, I guess.
When I was broke, I played an Mim jazz bass for about 10 years and was content. It was my only functional bass. Maybe that has something to do it that too...
Sorry for the rambling, been a long day.