Hobo said:
Yes. This. I hear this kind of stuff online all the time, and I think "how does that impact your table? How does that impact your ability to make houserules? How does that impact you at all unless you are an actual publisher?"
So far, I've yet to hear a coherent answer to any of those questions.
While I don't agree with this as a reason by itself to not get 4e, I do somewhat understand where (some) of those folks are coming from. Many are likely like me, in terms of purchasing habits. I don't buy most of the shlock WotC puts out. Especially adventures, which they are horrid at writing. Most of my purchases for supplemental stuff and adventures were via 3PP, because it was BETTER than WotC.
Now, that is not quite as likely, because of the GSL. Established companies don't want to risk some of the so called "poison pill" clauses in the GSL, which is perfectly understandable! And while there will be some new companies stepping in to fill the gaps, I think most of us recall some of the early 3e 3PP stuff and its...umm...'quality'.

(Though I could pray for a 4e "Death in Freeport" to kick things off with! )
Which could result (as another poster mentioned) in giving Hasbro the excuse to kill the GSL in the name of defending their brand.
I like 4e. I will likely support it, somewhat (though I hate WotC's marketing strategy and won't be buying every single book they churn out). However, I am saddened by the possibility of fewer 3PP being able to jump on the 4e wagon.
In that respect, I can understand folks passing on 4e to stick with the older edition and the support it WILL be getting from 3PP.