Except London...![]()
Of course

It is unreasonable for EMR to anticipate that the 810s would be as late as they've proven to be, and it's a cop out to just say "I'd have made Hitachi deliver on time" (we all wish we could've done that, especially Hitachi's leadership).
Specifically, you've criticised the 360+222+180 plan in general (should that be "Plan 762"?), not the immediate issue of 222s departing before 810s are in service
The key decisions that I think led us here were
1. Cancellation of MMLE* due to the unfolding carnage on GWEP
2. Ending 2+8 HST operations on the MMLE by introducing the clock-face timetable we have grown to love
3. Not to spend £££ on HST RVAR compliance (eg power doors), and not to continue with non-compliant rolling stock
4. Cuts made in response to reduced income and demand during/after the pandemic
Which of these decisions should have gone differently?
*Specifically the 2017 cancellation, not all the other times it's been cancelled
I think its all part of the problem, fueled by the ridiculous way rolling stock is managed in this country, so yes, getting rid of 222's before their replacements are ready is nonsensical.
No rail provider can predict how easily a fleet will settle in, which is why cascades ought to happen when existing rolling stock has been released.
I don’t have the numbers to hand, but I’d bet that Derby, Sheffield, Leicester and even Nottingham have fewer passengers to London than Luton Airport Parkway, Luton and Bedford.
I don't doubt you, but I would have expected the Luton's to be mainly soaked up by Thameslink, so not particularly relevant to IC provision.