As always, multiple things can be true at once, Tourism to the U.S. is down, Disney is providing discounts for the Summer (expecting lower attendance), there is a level of economic uncertainty, it is hot/rainy in the summer months, and foreign tour groups are still visible in the parks - (I was just there as well).
Likely Disney and Universal understand the trends impacting them or not - probably better than most - and earnings will begin reflecting the actual impacts (positive or negative) over the next two reporting periods. So, it will be interesting to watch.
Personally, I am not opposed to crowds or pricing in general trending lower - whatever the reasons - but that heat is tough to beat.