Since inertia no longer appears to be a concern in the Star Trek universe, I don't really see the problem with stepped turboshafts and sharp corners. Surely it must be trivial for the turbolift to do a fifty-gee turn at a corner when the starship apparently can do five thousand gee turns without as much as causing Kirk's coffee to spill.
By the same token, there's no particular reason why Kirk's feet should remain pointed down throughout a long turbolift trip. He couldn't tell the difference even if the lift did cartwheels to clear a particularly tight corner or hop over a GNDN line.
Whether the stepped shaft often portrayed on the neck of the TOS vessel is an accurate representation, or a symbolic one in the style of London tube maps, it's difficult to tell; these "cutout" or "MSD" views supposedly exist to serve an in-universe purpose, for which perfect realism would probably be counterproductive in most cases.