I guess you have to pull this post apart;
the J2534, yes, you could give some discount to MaxiSys users. It's an addition which can also be used separately and is quite fundemental and therefore also is part of the Pro version. If people want to upgrade to the Pro by buying this extra it could be a little bit cheaper then the separate price.
For the scope; it can ONLY be used on a MaxiSys I guess, so why would they discount it? It's the price that goes for it and everybody buying it IS a MaxiSys user?