In terms of improving the environment it would seem like not driving/using public transportation trumps any ev or hybrid anyway.
It has the added benefit of not having to worry about range/changing on road trips. My biggest concern with it is stale gas in the tank from not using the gas engine that much, I don't think I've filled the tank more than three or four times in the last year.
As you point out, not driving is better, but for many people it's not possible due to the public transportation systems/bike paths not being particularly great in most of the US.
Unless you're leaving the gas in your modern car for >~1yr I probably wouldn't worry about it too much.
Toyota argues that batteries are constrained and that for one EV they can make five PHEVs which will reduce emissions more than that one EV. It makes sense on paper and they have a wildly popular PHEV in the RAV4 Prime but they haven't even remotely scaled to meet demand, so it feels more like we are replacing one EV with one PHEV while the other four buyers go ICE or plain hybrid.
I think there are a lot of people for whom the math works out on Toyota PHEVs at MSRP, they might be worried about range anxiety, they might travel a lot (56mpg at US prices generally costs less than super charging), they might not need a home charger because they can charge up at work, they want a super-reliable car they can drive into the ground, etc.
but a lot of that is thrown out the window if you have to get on 10 waitlists, wait 6+ months, and pay $10k over sticker.
M3 is $38,990 + $1,390 delivery fee, minus the tax credit comes to $32,880, or about $890 cheaper than the Prime. Come January 1st the M3 will be almost $3k more unless changes are made to the tax credit.
Other problem with hybrid is you have all the maintenance & failure modes of ICE plus the maintenance & failure modes of EV in one vehicle. Statistically they have the highest rate of vehicle fires (this makes sense, you have the risks of both ICE & EV under 1 hood).
You'd think so but in practice most hybrid designs allow for some fairly radical simplification compared to your average ICE vehicle. eCVT transmissions are stupid simple and reliable compared to traditional automatics and also have the benefit of replacing the starter and alternator. The high voltage system also let's you easily replace failure prone belt driven components like power steering pumps and A/C compressors with electric versions. Hybrids can also hit efficiency and power targets while naturally aspirated, avoiding the need for turbos and all of the associated complexity which is very common in ICE cars.
Hybrids generally also have longer maintenance intervals because the engine only runs ~2/3rds of the time relative to ICE for a given distance driven. Rotors and pads will also last much much longer.