You'll find that most astronautical engineers will quietly put down the shuttle (which is really a re-usable space station, not a spacecraft in the "star-wars" sense) as a very expensive way of achieving something that was done much more efficiently with a lot of 1960s / 1970s Saturn V / Soyuz / Molniya technology. If it was otherwise, the US wouldn't still be launching most of it's satellites on old fashioned rockets.
The capability to manoeuvre in orbit is extremely small and limited to very small orbit corrections for matching, it's simply not possible to lug up enough fuel to make major orbital corrections. Also orbital corrections are basically limited to (a) forward thrust = a high higher and slower, or (b) reverse thrust = a bit lower and faster, (c) lateral thrust = a very slight alteration to the orbital plane.
The Launch window is defined in order to hit the right orbit, at the right stage, get that badly wrong and you end up several hundreds of miles out - which is not a great problem if you just wanted to be in orbit, but to match orbits with an existing satellite presents a few difficulties.
The other point of-course is that because it isn't an aircraft that can just take-off and land(whatever NASA try to claim) there are hundreds of support staff and organisations that need to all get organised for the same time, which restricts them a bit to slots planned well in advance.
G