For shirt pulling there is a continuum. On the lowest level of the scale there's contact that's either allowed by the letter or the law or by the current interpretations of the law. No player or fan realistically expects a free kick or a penalty for a small shirt tug. You might disagree that this shouldn't be the interpretations of the law, but this is the reality and obviously defenders will try to take advantage.
On the other end of the scale there's the blatant foul. Cynical, but to me not cheating. As a sidenote I didn't think the Suarez infamous handball was particularly bad either. It's cynical, obvious, punishable by the referees.
In between there is the cheating, but there are shades of grey.
For diving there's no real continuum. There's no cynical, but not trying to cheat kind of dive. There's no "diving just a little, within the regulations".
In addition to that for a shirt pull I think "at worst" you deny an opponent a clear goalscoring opportunity, of course that's bad, but compared to diving it's not as unfair. A diver might, in addition to gaining a clear goalscoring opportunity with a penalty, get an opponent sent off or booked. An added injustice on top of the penalty/goalscoring chance. I think that makes both players and fans understandably upset.
So yes, I do think it's more devious and sneaky, although I accept that to some extent it's a cultural thing.