Keep the old gems. It's better for new, returning and basically most of the playerbase.
A lot of the old gems will actually be worse for newer players once the patch is launched, imagine trying to full gem something with old gems (they still have rng in 4.0) and on top of that the 4th, 5th, 6th, 7th gem slot taking anywhere from 500-2000 gold each attempt (plus still having a chance to fail).
Even if you keep old gems or remove them, 4.0 is not a good patch for a new, lower geared, or even average player, no matter how you look at it. 4.0 is definitely a "rich get richer" patch.
- If we keep old gems in the 4.0 patch, people will still have to deal with the RNG associated with them, on top of the additional gold cost to socket, which makes it harder to gear than it is now for new/undergeared players
- If we remove the ability to craft old gems but keep the existing ones in the 4.0 patch, there will be a finite supply of the old gems which will make them harder to obtain for not only newer/undegeared players but also for middle of the pack average players. Wealthy players will stockpile these and use them for themselves or sell at a premium.
(4.0 default change)
- If we remove the ability to craft the old gems, make them unrecoverable through mornstoning, and make the existing supply of them unable to socket, nobody will be able to obtain old gems except people who already had them in the gear and even then, you won't be able to upgrade that piece of gear if you want to retain those gems. This is really the only way to prevent new/average/undergeared players from getting price gouged, but this still isn't a perfect solution because it doesn't really allow them to catch up to the top 5% stat wise in the same manner.
Regardless of how you look at it, 4.0 is an awful patch for pretty much everyone but the top 100/established/wealthy from a balancing standpoint. All of the potential solutions make it harder for people towards the bottom of the spectrum.
I feel that in the current state of the games and percentage of Battlerage users Some of the gems added reduced cast time such as Frigid tracks which is difficult to cast in mid combat where as battlerage users have instant mobility and attack skills available at all times. Personally I feel gems like that being removed would make the game unenjoyable for a lot of mage users especially any newer mage player whom may not have immediate resources to lower cast time and already have enough of a hard time surviving in the current meta.
Frigid tracks gem still exists for belt slot, it reduces frigid tracks cast time by a percentage, not a flat amount. There isn't a reason to keep both old and new frigid tracks gems.
The new lunagem system was one of the best things about 4.0 The only complaint I had was losing some of the ancient/eternal gems. i.e zeal gems Maybe we could just keep those?
zeal gems are not very balanced in a meta of inflated critical bonus and rate, zeal itself was progressively nerfed in essentially every patch from 4.5 onwards for this reason
I like some of the new gems a lot, but would like to have the option to do the old gems too. I don't know if it's possible to keep both in the game. Would dungeons then continue to drop the old style mats? There would need to be a source for the older mats, or pehaps those drops can remain as they are and the conversion system can be ongoing instead of just something for the transition.
More than likely they would create new recipes to make the old gems with the new mats, having two different material systems is bound to be extremely confusing and not to mention, annoying to work around.