If you know of other manufacturers with similar problems please share
We have two soft tops - a Lotus ( loud groans from the rest of the forum

) and a Smart roadster. Both are more directly comparable with the moggie than a mass production soft top from say BMW, particularly the L car where production volumes are similar. Neither of them is 100% watertight but neither leak more than the odd drip when parked in rain with the wind in a certain direction. Neither leak at all when in use.
Both have been reliable. The Smart 100% so and Lottie has just disgraced herself once when a plug dropped out of a socket.
So really the leakiness of Morgans isnt up to snuff these days but then the hood construction and side screens on a Trad is straight from the 30s so what do you expect? Its either "not up to scratch" or "part of the charm" depending on your outlook.