Would agree that the constant descent, go-around immediately at MDA+50'.... is generally fine for everyday ops.
However, there are times when you have to be down and dirty at MDA to see the runway.
Go to the alternate...well yes but suppose you ARE at your alternate or your alternate has gone below minimums, and you MUST make the most of your situation. If the "fly level at MDA" until the field is sighted is not practiced in the sim (yes, even with an engine out) and the particular situation demands that this be done before dry tanks...well you would be up the creek without a paddle, or SOL.
Or, take another situation...on approach to the the old HKG airport, IGS trips off (very heavy rain) and the only other approach is the CC NDB. This particular approach requires crossing CC NDB at 1500', descending to (as I recall) 745'msl and then tracking for 10 miles toward Stonecutters NDB where a right 130 degree turn is required toward RW NDB and the runway. If you tried the "constant descent, miss at MDA+50' scenario, you would never see the runway. Extreme case you say, well yes but there are many non-precision approaches where if you do not fly level at MDA....the runway would never be sighted.
This is why the FAA requires level flight at MDA to be demonstrated, and yes, with an engine out. No one said it was always going to be easy at the pointed end.