The way I see it is each to their own.
It's easy to get pulled in to being judgmental, but I agree with the comment on classes of TM and I know that there is a massive range of the strength of TMs and how far a domain name could infringe on someone else's mark.
Then there's the whole deeper level debate on can someone own a word? Just like owning an idea, and if it really helps innovation...
Anyway I digress - as for a forum and changing rules based on an increase in TMs that could harm the industry, basically I haven't seen anything that I think is harming the site/domaining industry.
I confess when I started out I had one or two obvious TMs and let them drop. Even now, there may be one or two which are borderline:
I'll give you an example: fearfactor.co.uk
It's a familiar phrase, but arguably associated to the TV program.
I hope people don't respect me any less for this confession?
Two questions though:
1. Should this type of domain be allowed on the board or is it an example of a name that would need to be moderated?
2. Who decides where the line is?
Also I might not be popular for saying this, but we want to keep the 'industry' professional, and nice and clean, but almost every single one of us is/tries to be a hawk at times. By the nature of what we do we want to buy something as cheaply as possible and sell it for as much as possible (domaining/not developing)
Before you say it, I don't agree that this is the same as most other business.
I think most businesses focus on client relationships, repeat customers, building a business, feeling good about what's happening in the business and a load of other things...
When I develop websites (especially forums) I feel this, but when I buy a domain cheap just to sell high then I think all those transactions are void of any respect.
I know that I'm digressing a lot here, and I'm not focusing this on you Edwin (with all of your lovely, mouth-watering generics

), but as some would take a stand against people holding 'trademark' domains, people on the other side (non-domainers) often look in and see someone with hundreds/thousands of domain names (maybe generics) and they don't respect the portfolio owner. They just see a waste of potential and a bunch of names that they see as costing £5 but the person is selling them for £5000 and he/she has thousands of them. (Of course often the portfolio owner paid more than £5 when they acquired the domains).
I guess to summarise all of this stuff I've typed here, I'd say that I think holding obvious trademarks or typos isn't a good thing, and will likely get you into trouble at some point. But I think there are grey areas of trademarks. People learn and often listen to good advise: I've learnt a lot on Acorn. I also (perhaps wrongly) believe that receiving a solicitor's letter about a domain that infringes a TM is a domainer's right of passage.
Although we want a professional/clean industry (so that we can sell our domains for even more money to end-users! In a way very ironic don't you think?) maybe we need to be aware of the fact that we are hawks at times and that our perspectives (how domainers should operate) and others (especially outsiders: 'domainers are cybersquatters', or 'what a shame that person holding all those domains that should be developed into websites') can be very different.
If the main reason to create a more professional/clean industry is to bring more customers in and make more money, then there's more than one issue (trademarks) to consider.
My last thought, the reg fees would probably go up a lot if everyone was more selective about the names they registered.
Added: Edwin - I can't believe you're selling
this name (you should be ashamed)
(I'm only joking, Edwin isn't really selling that name, I just manipulated the url - trying to insert some comic relief after my essay above)