^^^^^Anything is easier to maintain than a bunker. No really, I'm not joking.
That being said, berms/blobs/what have you would never be maintenance free.
I use many grass bunkers, basically shaped like bunkers, but without sand. When I first started golfing in the 1970's, the Chicago public courses I played had many former grass bunkers, now grass, and I guess I grew up believing those were natural parts of a golf course.
I cringe when I see scalp marks on them, as I did this weekend at one of my courses up in Kansas. Whenever I measure those scalp areas, they exceed the long recommended machine mowing maximum steepness of 33%. Some measure must 36%, maybe 40%, a result of some aggressive shaping or poorly drawn plans, i.e., if a grading plan shows a slope at steeper than 33% through careless drafting (or design) they end up scalping.
Some things can be avoided with a proper plan. It is hard to show a subtle transition slope at the crest, and those areas are the ones that tend to scalp, in addition to the overly steep slopes. In the field, we generally believe that if construction tractors and machines can get over it, mowers will eventually get over the slope, too, but some times we "missed it by that much." (Insert Maxwell Smart voice here)
Yes, they say mowers are better than ever, but probably, any course that can't afford too many sand bunkers probably can't afford the more expensive mowers that cover steep banks. And few public courses like that shaggy look, especially when it causes lost balls and ball searches, which slow play.
Which is somewhat a shame. I have always found that the steep banks provide artistic shadows and contrast. Also, the steeper the bank, the lower the overall feature has to be to still be noticeable as a hazard feature.