Yes, having T4 available too soon was actually identified early on, which is where the kernel nerf came from. From beta, I think the devs felt that it would take a lot-lot longer then 3 months for anyone to complete the kernel tree. Epitron was also supposed to be the bottleneck for T4 production, but they also underestimated how much material a corporation could also gather, so they added norgalis too; they havn't made any other changes to T4 production so maybe they are happy with the current rate.
But, history aside, I still feel the problem with stocking the market with T3+ gear is what has already been identified, that it's too expensive for open market buyers to PVP with, so the consumers here are PVE users. PVE users don't blow up stuff very often, so the sales depend on second accounts or new players for volume. T2 on the other hand would probably have a bigger market, but we ran into this problem last night. Because of the T1,T2P,and T3P costs you have to make and sell a min. number of units just to break even at the going market price. That is a T3 item at 1.5M on the market can cost 1.5M each to make if the run is small. The larger the run, the more the cost of the production gets spread out. But as indicated, the market isn't strong and repeating for T3, so making 20 items and only having 6 sell means you've lost money and tied up capital in 14 units. That calculation gets worse when you go to T4.
Edit: But you can't stop the chain at T2, or your T3 run won't be profitable either.
Large corps have alot more capital, so they can afford to wait 3-4 weeks for 20 units to sell, and continue to produce. Small indy corps, the ones most likely to put T4 on the market can do that with a 'few' items, but in general still need to keep stock turning over.
tl;dr - More demand on the market will result in more supply. Small indy corps can't carry the market waiting for the demand, the chicken has to come first. NeX, being a large corp, actually had the potential to be the egg and stock the market, but instead chose to stock their internal market; and now the market is not just competing with a low demand, but a second market.