The centralisation of these games isn't the problem; it's the commercialisation by fans.

As a player of DnD or GW titles I can, within my local gaming group or club do whatever the heck I like with the IP for private use. Its only when I seek to monetise my creations that it becomes an issue.

Except these games are supposed to be fun hobbies and as soon as it becomes a job the fun wears off. I've been there and I'd rather not go back.

The easiest and most obvious way around these restrictions? Imagination. How about instead of trying to piggyback the successful IP of an established company you come up with your own?

My friend and I, disgruntled at what GW were doing in the 1990's developed our own game. We modified the ruleset of another title admittedly but we wrote everything else ourselves and played it within our gaming community.