You're right, can't go around saying things like that without having the proof to back it up. I'm fully willing to accept that it could be an imby perspective, or that I'm recalling the past in a rose tinted light. I think there's quite a few of us on here who, like me, were kids in the 80s and 90s and remember some 'all nighters' or days with multiple storms. These could probably even be narrowed down to a handful of events that we all experienced and had such an impact on us at the time that we're all here on these forums as a direct result! And so it could be that, in remembering them, recent years seem poor in comparison.
Yet I'm still convinced that there has been some fundamental change. It is difficult to get an accurate comparison. The number of days with thunder heard is just one indicator and doesn't differentiate between those 'thundery showers' vs a cracking storm. Number of lightning strikes would be a great quantative value but how far back does the data go for that? The European Severe Weather Database could be a good way to compare frequency of events, though there's problems with that as I feel more recent events will have been better reported. I would definitely like to see a similar paper to the one I posted before about the number of mcs'. I think the number and track of them could strongly sway me either way.