"replacement for 90% of the rest of the RN"
That's the sort of lazy talk that characterises too much of the debate around the carriers, that and the tired old line along the lines of "shame there are no aircraft to go on them, fnar fnar".
Most of the reduction in the escort force (we had around 50 frigates and destroyers at the end of the cold war) has arisen from an over-enthusiastic cashing in of a "peace dividend" since the late 1980s. The RN may have traded a small number to safeguard the carriers, but that results from a recognition that while a navy comprising only escorts would be good for flying the flag, it would be far more limited in its ability to deliver real military effect.
I'd agree the reduction in escorts has gone too far. But ditching the carriers isn't the way to address that.