I feel like users should do what they need to do to get the gameplay they want to see. It's no more "cheating" than what happens at the Legend level for the CPU.
If it would be easier to just lower solid hits and this is the one area that's driving you up a wall, then do it. No sense tinkering with everything else when you've narrowed it down to one issue that's nagging at your experience.
IIRC, I remember reading on here that difficulty level is like a "base" with the sliders moving from 5 as a "modifier".
So Legend Solid Hits @ 4 isn't like All-Star Solid Hits @ 4. The Legend 4 is like an effective 9 or 10 (or more?) perhaps in the internal "raw value" that goes into the calculations.
Raising the pitching sliders lowers the chance they'll get a good read and good timing on your pitches, but doesn't change what happens if they DO get that good read and timing. That's where Solid Hits comes into play.
Then when you consider that Legend probably has a higher chance of getting that good read and timing - quality of contact is going to be the saving grace without introducing things like too many K's, etc. I'm gathering from your post you're fine with most of that, just that they are always get good wood on the ball.
In other words, I'd lower Solid Hits - significantly if I had to, if I liked everything else on Legend except this one aspect.