That was actually one of the major selling points to me. It's much easier to add than to subtract. I had considered, for my DL campaign, doing 5e but removing subclasses to lower power levels, but balance was a bit off when I did that. Whereas with OSE, I can add the extra features (classes, some special abilities) without breaking the fundamental math and/or systems.I like that OSE is kinda safe haven for making things for OSR games. More easily used in your flavor of B/X or BECMI or ODD variant.
A secondary nice thing about OSE is that it has gotten some degree of name recognition even in circles that have not really heard about other retroclones.
It seems to me that OSE is an easier sell to players than even B/X, depending on where you go looking.
When I run a D&D game anymore it's with C&C for the same reason. Plus, it's so easy to convert any of my old AD&D 1e or 2e adventures to it. I've never looked at OSE so I can't compare but I came really close to backing the last Kickstarter.I looked at it and even did a few solitary D&D session with it. It is really a well made document. Much better than flipping back and forth through my old Basic and Expert books.
But ultimately I prefer the AD&D1e (Greyhawk) vibe of C&C.
For a different perspective, and one view on where I suspect many part ways with the old school mentality:3. Task resolution. Good heavens, this is quick. You’re an elf and want to listen at a door? Roll a d6, you have a 2 in 6 chance of success.
It's because you're focused on playing your character and trying things in the world, poking around and seeing what you can do...instead of worrying about feats, subclasses, and doing the optimal thing.Isn't that the classic D&D experience? Understanding only half of it, and finding it amazing?![]()

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.