All i3's can utilize 240vac, level 2 charging.
The reason there's a way to limit the charging rate on those with 120vac circuits is to handle a shared circuit...i.e., say in the garage where the garage door opener is on the same circuit. If you let it charge at maximum, and then opened or closed the door, you might overload the circuit breaker. A 240vac circuit is typically a dedicated circuit to one thing, and thus, the charging rate isn't as big a factor (at least in the USA).
THere's a slight disconnect in the maximum rate. The EVSE sends out a signal indicating how many amps it has. There's nothing in that signal that says what voltage it is - the vehicle senses that. SO, as was discussed earlier, since the EVSE limits how many amps it has, and the car will honor that, it also won't draw more actual power than it knows it can handle. So, the car has a limit of 7400W in the USA on ACV inputs, but is responding to the maximum amps the EVSE says it has. If that were 120vac, that would be a different amount of power versus say 110, or 130, or 208, or 220, or 240. In my case, my typical power is 248vac, so at 30A*248v=7440W, or more than the car can accept...the car is the limit on one side and the EVSE is on the other. Think plugging in a 100W light bulb, even though a 15A circuit can provide 15*120=1800W, it works just fine when you only draw 100W from it. In the case of the i3, you can dial down that "100W" to say about 50W in the software so it might not pop if you also had a space heater on the same circuit.
So, yes, a larger EVSE could shorten your charging time. However that EVSE is powered, it should not use more than 80% of the available power. On a 15A circuit, that's 12A. On a 20A circuit, that's 16A. On a 40A circuit, that's 32A, and so on.
In a home, your limiting factors are the installed wiring and protection circuit then coupled with the EVSE you selected. Never install an EVSE that can provide more power than the wiring and circuit breaker is designed for. Note, some EVSE's can be adjusted internally to announce they have different amounts of power. One of those, as long as it didn't exceed the wiring, could be dialed up or down to suit your available infrastructure. The vehicle won't pull more than the max that is announced, in any case, and, if you sprung for a really large one, would not max it out.
Plug-in hybrids may not have as high a charging rate as the i3, plus, they tend to have a smaller battery, so it's not a big deal. When using ACV inputs, the limiting factor is the DC power supply in the car...it only draws some max. Just like the light bulb example, if the source has more, it won't hurt anything.
In some markets, the maximum ACV charging rate is 3700W. All vehicles in the US have two modules installed that bumps it up to 7400W. A few places have a different internal AC-DC power supply.
When using a CCS unit, you bypass the AC-DC power supply, and are feeding DCV directly into the batteries. That data communications scheme is a bit more complex as it controls the voltage coming out of the CCS unit. REgardless, though, the car won't pull more than what's available, and having more isn't an issue.
2011 535i x-drive GT, 2014 i3 BEV