At present, I don't really see any real merit to Diamond Plus. Having things like cheaper redemptions during blackout periods is nice, but doesn't really justify going at all out of my way to get that status. Now if KE were to keep more or less their current program and do a status match, then Diamond translating to Morning Calm would be a favorable deal to OZ Members in terms of miles (40k to to reach Diamond in OZ Morning Calm on KE), but it would be a really sour deal for D+. But then matching D+ to Morning Calm Premier would be really unfair to existing KE members who need to collect a whopping 500k lifetime miles vs 100k for D+.

Really, KE will have to revamp its mileage program completely and we will likely get some idea of what that should look like after June. They attempted a massive devaluation in 2019 that was to take effect in 2022. Ultimately, it was massively criticized and KE came under government scrutiny which led them to cancel the changes. You can read about it here Korean Air announces major frequent flyer revamp. Under that plan, KE wanted to introduce 4 levels
1. Silver - equivalent to Morning Calm - at 10,000 miles in 12 months
2. Gold - equivalent to Morning Calm Premium - at 40,000 miles in 12 months
3. Platinum - equivalent Million Miler - at 70,000 miles in 12 months
4. Diamond - new level- at 100,000 miles in 12 months

This program was rejected by the same authority that will review the new plan in June, so KE will have to make changes, but I think this scrapped plan can give some hints as to the direction in which things will head.

Returning to your question, if KE introduces a new program and if it is anything like this 2019 plan, then Diamond Plus might get you matched to Platinum. If that were the case, I wouldn't really see the big merit over just securing Gold, enough to get Sky Team Elite+ benefits.