Was volcanic activity more prevalent when the dinosaurs roamed?
There seems to be indeed reasons to believe in an enhanced volcanism during the Cretaceous at least.

The Cretaceous timescale is indeed peppered by the formation of large igneous provinces (known collectively as LIP; short review in Ogg &amp; Hinnov 2012a): Parana at ca. 135Ma, the Ontong-Java Plateau at ca. 125Ma, the Kerguelen Plateau at 118Ma, the Caribbean Province at 90Ma and of course the famous Deccan Traps at the K/Pg boundary. In addition to those large events, they were as well other more minor pulses of large-scale volcanism during the earliest Cretaceous (Shatsky Rise), and at ca. 87Ma (Madagascar Traps) and ca. 73Ma (Sierra Leone Rise).

The 5 LIP, though localized to a specific region each time, had a global impact on the climate and on the oceans, as seen on $\delta ^{13}C$ curves for instance, or during the different episodes of Oceanic Anoxic Events.  

As far as the pop culture trope is concerned, most of these volcanic events were partly underwater (Shatsky Rise, Sierra Leone Rise, Kerguelen Plateau, Ontong-Java) so I doubt dinosaurs were roaming around active volcanoes. It is probable that the trope originated instead in the idea that the Deccan Traps triggered the end Cretaceous mass extinction (i. e. the disparition of non-avian dinosaurs, in particular).

In comparison (see Ogg &amp; Hinnov 2012b), there were only one LIP forming during the Jurassic in the Karoo Basin (South Africa); if we ignore the Central Atlantic Magmatic Province which formed just below the base of the Jurassic (it may or may not have caused the end-triassic mass extinction).

Ogg, J. G. &amp; L. A. Hinnov, 2012a. Cretaceous. In F. Gradstein et al (Eds), The Geologic Time Scale 2012, Elsevier, Amsterdam: 793-853.
Ogg, J. G. &amp; L. A. Hinnov, 2012b. Jurassic. In F. Gradstein et al (Eds), The Geologic Time Scale 2012, Elsevier, Amsterdam: 731-791.