It would be better, if it had real rules, but how many people play GP2 and GP3 regularly when it does not have all of the rules?
How many people play/played games for consoles that have hardly any rules at all.
The whole series is a steady progression. In GP4 the gameplay, graphics, tracks, pit-crews, marshalls, and various other things have been dealt with.
GP5 may include a safety car and jump-starts. It may not. If it does not then that will be because of other improvements. Look at the difference from 2-3 and now from 3-4. The series keeps improving, and will continue to improve. If the game was to include everything we would never see it, as it would be getting constantly developed and tweaked. There are new rules every year so these would have to be catered for. Lets just be happy that GP4 is out soon(?) and we can all play an even more realistic F1 sim
Bazza