I don't think Universal lacks family rides as much as it lacks stuff for really young kids. Their rides are more intense compared to your average Disney ride, but that is what makes Universal unique and it is what their calling card is. You're right on most of the other things though. Once Diagon opens they need to focus fixing up IOA and not just Kong. They need to do something about Lost Continent and that god awful walk between MSHI and Toon Lagoon.
I do agree that they have a few family-friendly rides (Spidey and Popeye), but the rest aren't something a little kid would usually clamor to do
but really if you're under 42", you're not going to ride that much at IOA. and there's also adults who either don't like thrill rides or can't ride them, but love the theming. A few all-ages dark rides wouldn't hurt IOA's bottom line.
But I definitely think the park lacks enough attractions that everyone can do together. IOA could use its own POTC, its own HM, its own Big Thunder, its own Space, etc. Right now, there's 3 truly family-friendly rides (not just kiddie, but not just teen/adult) - Spidey, Popeye, and Cat. The rest either have high height requirements or wouldn't exactly entice a 5-6 yr old to go on (looking at JPRA)
A family dark ride and show in the front area of Toon Lagoon (potentially a unique flat, too)
Kong E-ticket between Toon and JP
A family coaster and Discovery Center dark ride for JP
Wonka replacing Lost Continent (the glass elevator E-ticket and chocolate factory family boat ride had me sold... better than what's there currently)
Seuss getting a much-needed expansion (plot next to Cat and maybe a couple repossessed soundstages from USF - Lorax dark ride, Grinch "big boy ride". and yearround show)
IOA shouldn't focus on primarily thrills, just like MK shouldn't focus on primarily kids. MK needs some E-tickets and thrill rides (immersively themed, of course) while IOA needs some more family attractions to start developing that nostalgia with its young guests. Both would do well to balance their parks out to provide an enjoyable experience for everyone.
But... :focus: Toho would be doing itself a favor by letting Godzilla get an attraction. Seriously, aside from the Godzilla film this year, what have they even done substantially with the IP since 1998?
More importantly, these two attractions need to be reworked...
Cat and Seuss Trolley. Both need some hefty upgrades and tinkering so Cat can be all-ages again (36" for a dark ride that would have no height requirement at Disney is just sad... rework the scenes so spinning isn't necessary to take in the story) and Seuss Trolley can go back to a 34" height requirement. It just shouldn't have the same height requirement as Spidey