I just dislike the whole "rep" thing more than I dislike multiple guilds. It creates problems with guilds wanting you to rep them all the time.
I agree that's annoying, but I don't think its a serious "problem" per se. Those guilds have no leverage except to kick you out of the guild, depriving them of that Influence anyway. Personally, I do what I want: my influence goes where I feel its most deserved or appropriate, and if a guild doesn't respect that, I don't want to be there anyway.
Forward to GW2… it is just a totally different game. I tried being loyal to one guild, but it has failed several times.
I'm pretty neutral on the multiple guilds system but I feel like any loyalty to the guild one feels will come from the friendships you form and experiences you gain together, rather than being enforced via game mechanics. If you had transplanted your GW1 guild person-for-person into GW2, do you really think you'd be less proud of it or less loyal to them in this system?