Eh, rotating them by hand and not feeling compression isn't the biggest of deals with small engines like this. I've got a couple of Magnum 52 4-stroke RC airplane engines in active flight rotation(IE on aircraft I fly regularly). One, an engine I'm the only one to ever put fuel and fire to, has so much compression at hand flip speeds that I will cut my fingers on the prop when priming it if I'm not careful. The other one has so little compression at hand flip speeds it's as if the glow plug isn't even installed.All engines I made: they have to have good compression from the start - and I think that's the right way to make an engine - no matter how big or small the engine is.
Both engines run flawlessly. The softer of the two is a complete starter queen, I'll grant, but they both run fine and both fly their respective models with grace and authority.
It can be incredibly satisfying to feel that 'snap', but as far as how the engine runs is concerned, it's not as critical as many think.