It's kind of more of the same IMO. Back when the e90 was out the 335is and the 2 series both shared the same DCT that was used on the M3. They just didn't have all the M bells and whistles.
The S58 is used today on the X3/4 M because SUVs have gained a large market share and to not use the engine on those M models wouldn't make much sense.
The seats are a mixed bag; in the UK for instance the M240i gets the same M Sport seats as the M3/4, but in the US the M240i gets the regular seats. This also isn't anything new, they do this depending on what market it's in.
I do however agree regarding cost cutting with the rear brakes. They changed the design for the parking brake which removed the drum style brake that was housed in the rear rotor hat and integrated it into the floating rear caliper. This however meant they couldn't just install larger fixed caliper brakes without having to also redesign the entire parking brake. So as a cost cutting measure they just painted some shitty floating calipers the same color as the front brakes so they don't show the raw iron and become rusty after a few years instead of developing aluminum fixed calipers like they offered on the last generation of cars, including the non-M ones.
They will argue that the rear brake is more than adequate in their testing and some will be OK with that. Others like yours truly call bullshit, because a fixed caliper provides more consistent braking, more clamping force and you can easily swap out the pads without having to remove the entire caliper.