Let's put things in perspective: My Honda Goldwing had heated seats and I very rarely used that gimmick - but the few times I did I loved the option to switch them on.
I have no heated seats in my 3Wheeler and I have not missed them yet.
But a Honda is a Honda and a Morgan may be more senible when it comes to Murphy's law: what can go wrong will go wrong (therefore no heated seats draining battery and rectifier)
They draw almost nothing from the electrical system. They are also so simple, I'd never worry about " if it can go wrong...". I have them and use them as do many of my guests. If they weren't there I'd survive. Use them less on bitter cold days when I'm dressed for the weather than on chilly Summer and Fall evenings when I'm not.