In my personal view, if anything, I think the DSG box suits diesels more than petrol. With a petrol and a manual box, it typically red lines around 6.5-7k revs, where as a diesel is all our of puff around 4.5k. Thus when trying for a quick get away, I used to find on my manual MK5 Golf GT-TDI, that booting it away from the lights meant that almost instantly I was near the rev limiter and snatching for second. It was light a rifle quick bolt action,.. first....click....second etc.
I now find with my last 3 DSG equipped VW diesel motors, that I can boot it away in any gear and the box just takes care of the gear changes far quicker than i could have. Coupled with the relaxed driving that ACC and DSG give you (bring able to bring the car to a complete stop in traffic) is wonderful (as it would be in a DSG equipped petrol motor as well). Also, it's very rare I find my box down shifting when I don't want it to (unless I am trying to accelerate with too much right foot), it's usually just fine, but maybe either the later boxes have better software, or mine has just learned my driving style better. Obviously in sport mode it will down shift (but then that's what it was designed to do), but in Eco and normal, mine is perfectly fine.
I agree there's a learning curve involved, especially if like me back in 2010 when I purchased my first DSG car (a Scirocco), I'd come to it from nearly 30 years of driving manuals, it took some getting used to. Wouldn't go back to a manual box now though, unless it was a proper sports car (but then most of them nowadays have auto boxes anyway).
Obviously DSG isn't for everyone and YMMV, and for a purist, a manual box is the only way to go for the ultimate "involvement", but if that's the case, you probably wouldn't be driving a diesel motor in the first place ?