Dream Theater somehow sounds a little dry cuz lots of their stuff is boring , not that it's played without emotion.
If you want to get that Petrucci's touch or feel , just imitate some of his solos that you think it his touch note by note , and you'll get it by time.
Actually I believe that's what Petrucci himself used to do, cuz I can hear other people's touch/feeling in some of his solos ... He get to sound a little bit like Steve Vai in "Under A Glass Moon" solo ,and you can hear Malmsteen's influence in some solos too , but there are still other solos that sounds unique.
Getting to play other people's music with a touch/feel similar to theirs can make you an extremely versatile guitarist.