While that may be true, I could barely get through Terra, I absolutely loathe the command deck system. I really don't get the constant change in battle systems, I know a different team made the off shoot games but sheesh keep it all similar.
Going through the series myself right now, I skipped CoM after an hour or so, the battle system isn't for me, I also ended up skipping BBS after finishing Terra's story as I didn't care about the characters nor the battle system in that either, the command deck is annoying. On DDD now and it uses the deck as well but it seems better so I think I should be able to get through it. Honestly I just want to get to 3 so I can finally finish this lol.
It's an extremely bad idea to skip Birth By Sleep. KH 3 is built on Birth By Sleep and you will be confused by a lot if you don't finish it. it'd be like skiping a New Hope and starting with Empire Strikes Back.
Like KH III isn't really a sequel to II but to what people think of as the spin offs like Chain of Memories, 358 Days, Birth By Sleep and Dream Drop Distance