I don't know if I would go so far as to say it is hoarding, but I do think many of us suffer from extreme collecting.
However, I don't know if it is a bad thing. If it brings a person enjoyment and doesn't interfere with paying your bills and fulfilling other responsibilities then there is no harm, right?
I personally never had toys as a kid and missed out on a lot, so now that I am an adult I have a lot to catch up on...at least that's my excuse. lol.
But at the same time, I personally am a firm believer that if you buy a toy or collectible then you should display it instead of just putting it into a closet where it never sees the light of day. But again, that is just my own personal opinion.