Um, not the same market as an iPad, completely different devices. Apples and oranges.
Yes, yes, I know, it wasn't ment to be comparable.
But my opinions on the topic:
I owned 3 Mac laptops so far and never needed to change or even think of changing the battery, althought the devices always were in daily, heavy use (scientific computation, 3d programming). One of the devices is 5 years old now, belongs to my mother since 3 years and still the battery is very good (maybe 20% less time, but that's still long enough for her).
There are some simple rules, how a battery must be treated to ensure a long lifetime: 1. Always fully charge 2. always let the battery go very low till you charge again.
So, for the current Pro Laptops, there should really be no complain about the un-ability to replace batteries. In fact, I manage several of them in the office and none of them had problems with the battery so far.
BUT:
The iPad is a different device. I think that the usual behaviour will be: Fully charche the iPad. Then, take it away from the dock and use it. I predict, it will not be used by too many people while on the dock, so for the rest of the time, this device is unplugged. As this device is designed to be a reader/browser/composer, it will be turned on mostly during long time-periods such as 2 to 6 hours. For shorter time periods, people would not consider buying this device as there are other devices serving this purpose. So this means that this devices must be recharced about every third day, presumably over night.
Now, not everybody is patient enought to do this so frequently, even more as the device itself (as mentioned above) is more or less useless when docked (except if you have a keyboard-dock, which costs additional money). So people will not fully charge them or just put the thing in the dock every evening to ensure it is charged the next day. I know that the memory effect is less on the new batteries but there still is some effect. And I think, there is a real chance of a battery failing (in the sense of showing a much worse behaviour than in the beginning) within a short time period such as one or two years.
That is what the battery replacement / device replacement is here for. It basically would be a good thing but sending in the device and waiting for a new one is bad customer service. I don't know how Apple receives such high score for customer service, I think it is very mediocre. But this is again off topic.
Rating positive or negative: First, the whole battery replacement thing sounds very uncomfortable and stressful. Second, this might actually be better to let the company deal with it instead of make it by yourself or by a third company. Third, well, what do I care, it is not a device for my purposes, so I will not own one.