So the old version is.... blah, blah, blah. We get it, we know that.
The new version is... blah, blah, blah. Still get it, still know that.
So the >v4 addons are gone because the old version is... or is it because the new version is...? Makes no sense either way. There actually are users that actually realized the old version's of osCommerce were at EOL status, many who were probably weighing business decisions on how and when to change software. Some of those many users were probably keeping an eye on the new V4, waiting until they feel they can change and build up to meet their shops already existing requirements that there existing osCommerce shop has been customized to meet. Do you not realize how many existing users may want to look back at the old contributions they have had installed through the years? Maybe they have an issue and want to see the original code for debugging, upgrading it to work on modern server setups, etc; Maybe they want to see what it would take to "modernize" an older contribution, or completely make a new addon based on just the "idea" of an old contribution.
Anyway you look at it, you alienated countless established users when taking down the old addons. You can repeat how the old version is "...", and the new version is "..." all you want, it doesn't help. People here are not dumb, they're smart enough to already know that. They're smart enough to make changes when their business allows, and they're also smart enough to find another software that will meet their business needs when the time for that change comes.
Now all that was primarily the shop owner point of view in me. So how about the developer standpoint? With a quick look, on the surface, the new code shares a lot of the old code. Even makes use of a modified theme system that was an old addon, looks like maybe BTS? or something similar. So that says, hey I can take some old addons, redevelop them, and release them as new addons! But, maybe like, y'know, Holbi had the same idea. So lets just cutoff access to all those old ideas and maybe release the most popular as new and improved paid addons! You have every right to do it too.
I feel like your going to push more away than you attract by removing the addons. Such a nonissue just to restore them, such a shit move not too. And believe me, people who know who I am, know I am all too familiar with shit moves and osCommerce.
Either way, best of luck.