I'm not arguing that they're not fine. What I'm arguing is that if you fit and use tyres with a lower speed / load rating than the type approved factory fit tyres then your insurance company will happily reject any insurance claim which they believe could have been compounded by the reduced capability of those tyres.
And I'm not going to resort to shouting to make a point, just confirm it with your insurers if you wish to reduce the tyre specifications....
I can see the safety argument your insurers could make for the load rating, but the speed rating doesn't imply that a higher speed rated tyre is safer at legal speeds than a lower rated tyre.
Ps: I wouldn't personally go with a lower rating, but there are plenty of GTIs and other performance cars out there being run on a shoestring with bargain tyres.
Also worth noting, the MOT is only looking at condition and wear of your tyres. The MOT regs don't mandate speed rating compliance with manufacturers specs.