This case it would be gaining an advantage (unless SC conditions apply) so yes, that would need penalties.
The difficult point is, that this still is human decision. Everytime there is something to complain, cus if he had it, 'Was it too harsh? No advantage was gained etc etc'. There are two camps on this, the 'strict-rule' fans and the 'action-over-penalties' fans. In both ways there would be complaints. The bottom line is that the stewards want to do what (they feel) is best for the sport and follow the mindset behind the rules to achieve that.
Same case, a friend of mine ran a red light once. Simply mistaken the straight light for the left light. Cops let him off with a warning, since there was no intention of wrong doing and there wasn't a seriously dangerous situation (praise roads at 1AM). Rules are clear cut there as well. Its always up to the interpretation of the guy in charge. Inconsistent? Yes. Well handled? Yes as well.
Bottom line is, there is no 'right' or 'wrong'. Its a gray area in which the stewards have to operate and the discussion will never end.
Just want to say that I do see your point
However, in more than one of the previously properly penalized breaches of this rule, there hasn't been any notable advantage gained.
Also, if the stewards start considering what's the best for the sport, you get situations where the top guys in the championship and top PR-guys (Hamilton, Vettel, Verstappen, Ricciardo and Alonso. Maybe Räikkönen) will get off lighter than others. That's not right at all.
I have no doubt that the stewards felt that they somehow had to keep the result, due to all the positive PR from having Hamilton win from 14th etc.
But this is a case where there is a precedence of penalties, even in cases where no real, clear advantage was the result of it.
If they had been given out 5 second penalties (or 10 second penalties, as a middle way between the Drive-Throughs and 5 sec penalties that's been given before) in all the situations, I cannot see there being any other discussion than fanboys being unhappy, as it would've been clear what the consequence it. Just like it should be.
This, Speeding in pit, pit exit, track limits, safety car speeds and double waved yellows are in reality rules that should be very easy to enforce. There isn't any room for "buts". Either you are speeding or not. Either you have crossed the lines or not. Either you are prepared, and able to stop at immediate warning or not. If you are inside, then no penalty. Are you outside, a penalty.
That is how simple it can be done, and it will get rid of all "FIA is biased" and "blah blah blah driver A is preffered" talk.