Well, as long as you extended the invitation...
Perhaps some have been less delicate than others in pointing out the consequences of your actions. Well, that's just your typical gun/car/motorcycle/etc. forum
Bascially, you had a collectible variant of the Chinese Type 56 that was more valuable before you started "improving" it. Now it's less valuable on the open market, even if you like it better, simple as that. I can see that having that pointed out upsets you and that's unfortunate. If I were on the receiving end of the information shared here, in the manner presented, I might be a bit tweaked too, but it wouldn't make the information offered any less true.
One point well made was that you could have sold it and bought 1.5 to 2 SKSs in equally good condition for use as one of your tools
that would have lost less value when modified. That replacement also would have been less scarce and collectible to others who find the SKS to be something historically interesting and more than just a tool, though most of us have one or more SKS that we would place in the tool, or everyday shooter, or even "open to modifications" category.
Since you mention your bedded Garand with added sights, another example (besides that) that you may be familiar with, would be stumbling into a modest priced purchase of a decent looking M1903-A1 with an ME of 3, and an apparently obsolescent 8x scope with a narrow field of view and slightly cloudy optics that was marked Unertl. You could have taken that rifle, put a new Criterion barrel on it, glass bedded the action, jeweled the bolt, added new bases and a 1.2K Leupold 20x scope, and probably improved its long-range shooting characteristics, but I don't think you would expect accolades from the Gunboards "American Arsenal" forum for your improvements to a $6000+ USMC Sniper Model 03-A1.
Your SKS is clearly not in the 6K+ range of the M1903 example above, but it sounds like you've been around a while, and you have to expect to take a few lumps if you walk into a forum dedicated to the SKS and talk about "restoring" and "improving" a scarce variant of the rifle that is the subject of the forum.
I don't expect you to appreciate the advice now, but perhaps at some time in the future you'll cogitate on it a bit.