What's so difficult about opening the oven door and putting the plates in for a few minutes? Or putting them in a microwave? The way some posters are in such high dudgeon about warming plates you'd think they were being asked to actuallymakethe plate.
Probably relates to your general attitude to fuel, which in its turn can be traced back to your upbringing.
To be fair, I think it's safe to say that I must waste electricity in all kinds of ways that don't feel like a waste at the time (for example, posting on this thread!), but putting the oven or microwave on just to warm plates when I'm doing something on the hob? That feels like decadence on the scale that [is reputed to have] brought about the Fall of the Roman Empire!