The irony being that most don't. For example, hybrid synergy drive is basically an alternate transmission design that replaces the complex clutch packs used to control Ravigneaux planetary gears with electric motors. The result is a more simple overall design.
Other systems are literally just beefed up starters.
I think it's more of a political thing -- if you've made the argument that "ICE = pollution = bad" then it's hard to turn around and say "but a little bit of ICE to extend range is good."
The battery + electric motor adds so much good -- regenerative braking, electric torque, good city driving experience, it really feels like every car that is now an ICE should be a hybrid, even if just a "soft" hybrid with no plug, like a Prius.
I would imagine most the complaints are for when the ICE actually powers a drivetrain. If it's essentially a generator to keep the batteries from depleting too far, that's not much extra complexity it all. Have a problem with the generator? Just swap it out with a new or rebuilt one from some vendor (if designed well such that you can do so). I'm seeing that a Tesla uses about 300 Watts a mile @ 55 Mph.[1] Honda seems to have generators much more than capable of supplying that need for under $1000.[2] I'm not familiar enough with electric systems to know how accurate that assessment is (whether the voltage requirements complicate it, for example), but that seems promising. Then again, I imagine if it was really that easy, Tesla would have put a generator charge hookup and exhaust ventilation capabilities in the trunk already.
Edit: Hmm, I'm definitely missing something, since the $1000 generator says it can go 8.1 hours on a gallon of gas, and it doesn't seem likely for that to translate into powering a Tesla for 8 hours of travel.
1: https://teslamotorsclub.com/tmc/threads/average-wattage-for-...
2: https://powerequipment.honda.com/generators/selecting-a-gene...
This is nonsense. The dimensions are wrong. Watts are instantaneous power. To be meaningful, you would have to give either kWh/h or kWh per mile or km.
Besides that 300 W is only 0.4 hp. Sorry, but that is just not credible.
The time component being on the mph allows the conversion.
On the other hand, using the correct units (300Wh/mile):
300 Watt * hour / mile * 55 mile / hour = 16500 Watts [a sensible unit] (or about 22 horsepower which is reasonable for a steady 55mph cruise).
Do that for an hour, and you get 16.5kWh of energy consumption and cover 55 miles, for an energy efficiency of 3.33 miles/kWh, which is in the ballpark (albeit low) for what my LEAF delivers (averaging a bit over 4 miles/kWh at average speeds somewhat lower than 55 mph)
The most powerful generator I see on Honda's site is 10 kW for $5400.