If you have to travel in Y or lowcost, then buy that middle seat.
You know it makes sense, especially as some of the charges may not apply to a spare seat.
If you are travelling as a couple, the extra cost is modest and given that airfares are lower in real terms, you're still getting a bargain.
No more behemoths inthe next seat
and you have space to put your luggage or your working papers etc..
I've just looked on the Ryanair webiste and for a flight Malta/Luton/Malta in 2 months, with a week stay, the cost for 2 adults is 152€ and for 3 adults 229€.
So if you buy 3 for 2, the return fare is only 114.50€, for 6 hours of flying and relatively a lot of comfort with that empty middle seat.
If I didn't have a load of miles to get upgrades on Y tickets, that's what I'd do for personal flights.