Erm 3rd ed did have the OGL to contend with. All those retroclones for example. The push was not there though as 3rd ed did mostly unify the fanbase as it was very popular and swamped the AD&D hold outs. The OSR revival one could argue is partly triggered by 3rd ed players going back to the retroclones as if you get burned out on d20 and did not like 4th ed there is really only one way to go.
You could have created a clone in 2000 or 2001. I think C&C was the 1st one to turn up in 2004. 3rd ed did have to deal with the OGL, everyone was to busy playing 3rd ed though.
But the OGL is for D20...NOT AD&D.
Most AD&D folks who didn't like the change either dropped out, lapsed, or stopped playing or were forced to convert.
the actual OGL as an AD&D machine wasn't tested and no one really thought it would be able to be done when 3e came out.
See Bill's post for 3e converter's who are STILL in denial about how 3e went about the same process as 4e.
The turbulence was FAR greater in my opinion when 3e came about in regards to the older players protesting the new system.
It was only LATER that people started thinking about whether or not they could recreate the older editions from D20 OGL's...at least in part.
OSRIC was actually the document wanting to make it so that documents could be made in support of AD&D without offending the trademark (it wasn't actually originally going to be a game in and of itself, just a reference document to enable other material to be made).
It was not based on OGL...but went into an area which no one went. They are LUCKY in that WotC did NOT pursue legal matters. They based OSRIC and much of the OSR is based on the idea that you cannot copyright a mechanic and you cannot trademark it. HOWEVER...formulas and other items in that regard CAN actually fall under some trademark laws (depending on the nation) and even fall under Patent law (which is far more important in regards to math, number tables, and many other items linked into RPGs). It's not really worth the time to pursue it for WotC overall I think, but in SOME nations a legal case could be made (but even if won, it's not worth it as 100% of 0 is still...0).
So in truth, 3e had the same process and marketing as 4e, and in some ways was even MORE offensive (WotC hatred among many old schoolers is so fierce as that they won't touch WotC products no matter HOW nice WotC is...to the present day even).
However, many of the 3e/3.5 fans do practice hypocrisy when they argue against 4e, because they ignore the precedence for 4e's marketing campaign that was created when 3e came out. 3e's marketing was the template for 4e's marketing.
People were more experienced and far more invested in OGL by the time 4e came out, and hence the D&D was in actuality competing with itself at that time, as opposed to when 3e came out.
So, 3e had the exact same marketing, and the same offensiveness as 4e, the difference was that there was no real alternative for D&D once WotC killed it off initially. 3e hardcores who hated 2e and older editions though, tend NOT to recognize just how the parallels were between the 3e marketing and the 4e marketing.
I'm not trying to make excuses here for 4e, but there are many who are so in love with WotC and hated AD&D, D&D, and Gygax so much, they've tried to flavor 3e's entrance differently then 4e.
I think if AD&D had continued to be published at that time, 3e and it's release could have turned out far differently. Hence, arguments that if Paizo (and I would include all the D20 products that continued after 4e was released) hadn't created PF, things may have turned out differently with 4e...I think may hold merit.
I'm not saying 4e would or would not have been more successful, but looking at 3e, which set the precedence (as in a legal sense), I think there may be some backing in regards to that idea.
PS: And despite what you may think, I am actually a very HUGE fan of PF. However, I find it rather ironic that when the same tactics were used in marketing 4e in regards to 3e, that you basically get the same reaction. When 3e was release you DID have the same reactions as 4e, and most of you who were there should be able to recall that. The difference was that there really wasn't any other alternative in regards to obtaining hardcopy of materials being currently printed for D&D unless you went with 3e. There WAS no AD&D hardcopy materials or even simulations of it being printed at that time. The closest would be Palladium, and if you're going to go with Palladium, you might as well do 3e anyways.