Bernie, let’s kill the confusion. I am guessing that your main thought is playing an arranger keyboard, and piano for enjoyment.
“I do not have a Steinway piano – hard feel keybed”. Right, but the same exercises will still help you get more freedom when you play the keyboard.

Playing music that is written for piano, again for enjoyment.

Left hand. Important. I try to play LH chords (IIm7 IV V7 I) in the same area, regardless of the bass root thing. If you have a sound in your LH, keeping the chords in the same area generally sounds better; and it is faster.

My thought of the LH:
For Big Band type of playing, and some others, the LH sound is very important. It answers and leads the RH. If I am using a solo trumpet my LH might be a sax sound working together with the trumpet solo. Picture a live Big Band, that is what’s happening.

What I learned form my guitar days. If I am playing a song like All of Me, my LF pulsates or held. If I am playing Misty, it adds color to the song by moving a single note, or adding color tones to the chord.

Enough, I get lost when I am sharing this kinda stuff.
Take care my longtime friend, John C.