So it appears that perhaps just classic old GTA style driving can get you away in Watch Dogs. And even if you do hack, you don't see it because it's behind your point of view, or if they show an exploding pursuer in slow mo it tends to make you crash because of the disorientation from the camera going from the explosion back to driving.
Do all sandbox games have this trouble? Dishonoured seemed to have this problem too, where just a few powers were needed to complete a mission and anything else was just getting baroque about the matter. And the sandbox - if it doesn't force the use of hacking, then hacking becomes a throw away, unnecessary gimmick. If it is forced, then you get less of a sandbox!
That's the thing about a sandbox - it tends to make everything not matter. Just another thing amongst many things. A bit like real life!
But seriously, do sandbox game makers need to start thinking about how they implement these things, giving a secondary layer of rewards for using hacking. So someone could be rated a supreme hacker if they wanted to, or maybe they might focus on conventional escapes and fighting.
But ultimately it's the audience that might have to accept that any new thing in a sandbox will, at best, have some incentives and ratings for it - it's not going to force gameplay to be entirely different, all by itself.