Personally, I don't mind the concept of the service - I know plenty of people will feel more confident with a Minnie Van (even though you order the van using Lyft, so ... 6/half dozen). I have a real problem with the price point - there is just nothing to support pricing it like that. A family of 5-6 not utilizing the car seats will have ZERO room for luggage - have you looked in the back of an on-site Minnie Van? That's what's in the cargo space - the two car seats.
$150 is just ridiculous, and I've paid for ridiculous things at Disney before but this is just ... so. ridiculous.