It has micro SD card, just put one in, or carry a dozen on you, it's not like they are big. (Yes I know they cost money, but so will larger internal storage)
As for the battery, don't think that's the problem, being a full PC running X86, it will drain the battery no matter what. If they put in one say, that can last 10 days, you are going to be holding a 3kg handheld the size of 15" monitor.
Larger battery = heavier. Then there will be people moaning about the size and weight.
Smaller console = people moan about the small battery.
The takeaway from this, people will moan, no matter what you make, you can't please everybody. I think they have done all the balancing from test groups and this is the middle ground with the current tech they can do.
I was sceptical at the start but having thought about it....the more this makes sense. The compromises they have made is nowhere near the compromise they could have done. It NEEDS to hit a price point and i think for the R&D to bring this to market, £400 / £500, I would think this is sold at a loss.
They can’t sell it at as loss as they end user is not restricted to buying games only from steam.
Edit: Off course it will take them a while to recoup development costs, but each unit will make a small profit.