Personally I wouldn't pay any premium for a table seat( they never have enough leg room for me) and at £40 the service is beginning to look unattractive when compared to the overnight megabus (normally pay under £20), split fares via Crewe or even railcard discounted Avanti fares. If you are faced with premium fares to a Central London Termius, Easyjets lower tiers of fares from Gatwick will still be attractive.
I'm not sure that is the main thing they're competing against, partly because there's only one of those (plus a NatEx doing the same) so you're only talking a maximum of about 100 passengers per day or so, and because passengers who are willing to take an overnight coach journey are as far budget as you can get without not bothering at all (an overnight seated coach really is the lowest "class" of travel conceivable short of kipping in the back of a bin lorry), so they will likely not manage to succeed in competing with that on price.
Of course, what you do show there is why that sort of supplement works - see speedy boarding, extra legroom seats etc - because some people think it's not worth the money and so benefit from a cheaper fare, but others think it's great and willingly hand over more, so you get both markets. I'd not like to see stuff that makes travel deliberately worse e.g. luggage restrictions or sham "check-ins" like the French did with Ouigo, but I equally can see the point in seating-related upgrades even in a single-class cabin, and indeed I usually take advantage of them to get an extra legroom window seat because that's valuable to me.
Laptop users may gladly pay a premium, for example (though 80x airline seats tend to be very good with laptops).
Yep, there are many downsides of the "good old" Sophia, but also upsides, one notable one being, as you say, that the tray table is a good size and has the pull-out laptop support, which when coupled with the very upright seat back means laptop use is well-accommodated.