My theory on this is that the MacBook Pro 14 and 16 models need the M2 Max as an option - and Apple probably decided to launch those with a new Mac Studio at the same time.
Or maybe, just maybe, there was never any real reason to expect Apple to launch new 14/16 MBPs only a year after the last models - a major re-design - were released. The only thing Apple religiously updates every 12 months is the iPhone - which is a very different (and more fashion-driven) market.
The Intel Macs frequently went 18 months without an update. The Mini went
4 years (2014-2018), and then
2 years (2018-2020, and that's not counting the i5/i7 Minis still on sale today) and then there's the Mac Pro trashcan... The
only Apple Silicon update so far has been the MBA (probably Apple's top-selling Mac & which was overdue a cosmetic re-design) and 13" MBP (which seems to be something Apple are obliged to maintain) - and
they had to wait 18 Months.
It was rather optimistic to think that - freed from the yoke of Intel - Apple would be on "M3 Ludicrous" by now, with new Macs like clockwork every September. In reality the M1 gave them a decent head start over the competition and also
freed them from direct, simplistic competition with the likes of Dell over who was first to adopt the latest generation of Intel processors and AMD GPUs.
While "analysts" may get the occasional genuine scoop, they also have monthly newsletters to fill & "no big scoops this month" won't cut it. Also, while Apple may leak clues about what is in development, turning those leaks into accurate predictions about actual products is very error prone. Someone leaks info about the lashed-up evaluation board they saw being used to test a new processor and it's "New Mac Pro features 113GB of RAM, 27-and-a-half CPU cores and a single PCIe x1 slot!".
If those CPUs are delayed anyway as the Mac Studio would then look like a very odd machine out as the MacBook Pros get M2 Pro/Max CPUs months in advance.
That's why I don't think we'll be getting a M2 Pro "Mac Mini" anytime soon, since it would be in direct competition with the Studio Max - but I really don't think Apple will care too much about their flagship MacBook Pros being a step ahead of the lower-selling Studio. It's not like they have a stellar track record of keeping their desktops up-to-date. Bear in mind that the Studio Max could easily have been released alongside the M1 Max MBPs, but instead we had to wait 6 months for any sort of "pro" desktop.