I think when realtrack/drums were first developed back then they may have thought they would be just used for just live accompaniment, practice, learning or backing tracks and not professional studio use as they are now.
Like the midi charts that were not originally recorded at the same time with midi pickups or DI boxes for dry tracks, so the original recorded ones had to have the midi notation added, I could be wrong but I think Matt had to transcribe some if I remember correctly ? The drums also were just recorded in stereo from the mixer so there were no multichannel drums and midi triggers on them to get midi also.
I do hope that there are original 48/24 bit recordings though ?????
The size of the drive these days shouldn't matter, I see there are 2T SSD drives now so give that a bit of time and they will be cheaper and up to 4t.
I thought also any tracks that have DI you should not have to include the FX ones on the drive or wav/aiff download, maybe just the compressed ones wma/m4a, or, biab/realband could just load an preset fx to go with the DI track ???
To have more control over RT soloist with what's been said before entering the notation and bb engine scans the RT midi notation to place those notes of the RT where you need them, it won't be ideal but will give something closer than random. You could have it like the multiriff selector to rearranged something closer to your notes and give you a lot of choices.