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European iPhones are more fun now
(www.theverge.com)
This is a most excellent place for technology news and articles.
To be honest I prefer to use a power bank, it's more convenient than having to swap batteries (i used to do that too) as you don't have to power down the device. And one power bank can power many different devices, so i don't have to buy a new one when i Change phones, and can use the same power bank to charge my earbuds, kindle, smartphone, and a variety of other devices, or lend it to someone.
Having said that, i did have my Nexus 6P battery degrade and had to be RMAd, lucky for me it was within warranty. Battery is the fastest failing component so being replaceable will go a long way in prolonging devices lifetime, but doesn't have to be user-replaceable.
Currently batteries are replaceable, but due to their design it's unlikely to be worth the expense. Forcing them to make it user replaceable ensures it's easy to do, and cheap - so even if you don't want to do it as a recharge mechanism, it is still to your advantage to have it so when your battery does inevitably deteriorate you can swap it out at your convenience.