What they're trying to convey to you is this:
It's ok to boycott a company provided you have some specific criteria you wish to see occur that can be expressed in definite terms. For example, I won't buy games from EA until: They drop Day 1 DLC and drop multiplayer in everything when it doesn't make sense.
You're not outlining specific criteria, you're offering a vague "I'm not paying them until something happens, and I haven't paid them because something didn't happen". That's problematic for WOTC, they can't please you because there's no thing they can do to that would make you interested in their products. From their point of view, you can't be reacquired because you have no specific complaint, and so time/money spent addressing things you bring up would be better used in addressing someone who does express a specific complaint.
I also think you've made a mistake in your assessment and position. You're correct that WOTC pays attention to people who aren't paying them, but only because they're paying someone who is visible to them. The people who left for Pathfinder may not be paying WOTC, but WOTC can "See" them because they know how well Pathfinder is doing.
They can't see you. If you're buying used books, the money you're spending is invisible to them. It doesn't appear in any revenue chain they can measure, unlike Pathfinder they can't estimate how many people are buying product through the channels you're using.
When WOTC holds meetings to discuss future endeavors, the data upon which they operate is their sales data and known or estimated sales of competitors. They don't refer to message board posts. So when WOTC is making a decision about the future of RPG's, unfortunately your voice is silent, you won't appear in any of their data. You didn't vote.
Now again, I'm *not* saying you have to buy their products, I'm just saying that when you state you're going to buy something used you really need to express a concrete event that would convince you to purchase at retail. This is how the PC market convinced Ubisoft to drop their DRM policies, they stopped buying Ubisoft product (> 90% drop in sales) and gave Ubisoft a concrete event that would change that (Get rid of mandatory DRM), and ultimately Ubisoft dropped it and people began buying their games again.
It's really a shame if you don't have a voice, you're an intelligent guy or gal who is very good with math. You have a lot to contribute. We're just saying that maybe it would be more effective if you expressed concrete events that would make you a retail customer again.
See, that's exactly what's happening with WotC. They were making as much if not more with 4E than they were with 3.5E, right up until the end of the first year. They had started right at the change over from 3.5E to 4E with quite a few questionable business practices. I could list them, but I think EnWorld has a policy against doing that. So many people stopped buying 4E books. Its true some of them were probably 3.5E fans being picked up by paizo, but if you looked at the sales reports (IcV) you would see that it didn't account for the slump that WotC was in. I personally think many people got fed up with the way WotC did business. I personally know many people who vowed not to purchase from WotC directly simply because of the things they did.
I also feel that until they prove they are not doing the same questionable business practices, that many people like me will continue to not purchase directly from them.
And just for your information we were very vocal about the things they did on their own forums and called them out for it. Guess what happened? Perma bans all around.