When you say you didn't think about about it until the decorator mentioned it, that suggests that you are not having a problem finding enough sockets to plug your appliances in and so can leave things as they are. Having said that, if you are thinking of selling in the near future, I have known prospective buyers ask about the number of sockets. Whether it would be a deal breaker or not I'm not sure.
The number of sockets installed has changed over time. In the 60's one single socket in each room was seen to be sufficient, with two in the kitchen.
In the 80's a single in the corner of each reception room became the norm, with an extra double in the lounge for a TV & video. Two singles in bedrooms in diagonally opposite corners and two doubles in the kitchen. In posh houses, they even started to put one in the hall and on the landing.
in 00's with the rise in the use of home electronic equipment the number has continued to rise. A report from the NHBC a few years ago said that a new build 3 bedroom house should have at least 38 sockets.
Of course with increasing technology, soon sockets will be wireless and you will be able to pick them up from Tesco for £4.99 and stick them on the wall with self adhesive pads. Then all of the homeowners that installed lots of wired sockets will have to fill in the holes where the old sockets used to be when they redecorate