Well in my opinion it is, it renders the entire camera useless. I would agree with you if the sort of batteries were used as on computer mainboards. These last 10 years or perhaps longer. Life of a camera should not be determined by an impossible to replace battery. I also wrote Fujifilm about this issue, let's see what they have to say about it.
Judged by your own standard, why wouldn't your opinion also be considered to be rendered useless? Try to be serious now. There are P&S cameras that never had ANY backup batteries, that would lose their settings with every battery change, yet they were very popular top of the line models that sold for nearly $1,000, and $1,000 dollars back in the year 2000 was worth a lot more than it would be in today's dollars.
If in your opinion, those cameras were useless, would you also consider them to be useless if they had internal backup batteries that were guaranteed to last more than five years? You may have had a camera whose internal battery died, but I own at least 6 Fujis that are between 5 and 6 1/2 years old and
all of them work just as well as the day they were first removed from their boxes. No battery problems of any kind. Not all computer motherboard batteries last 10 years either even though that was their estimated life span. Several of the 200 or so computers that I maintained had to have their batteries replaced after 4 to 5 years of use. Not a lot, but then not very many of those computers weren't upgraded and replaced by the time they were 5 years old.
If you're annoyed because you don't expect the HS20's internal battery to last 10 years, please confirm for us that if you got a camera just like the HS20 but it had user a replaceable backup battery, you'd still be using it either often or as your primary camera nearly 10 years from now. I can understand people deciding to pass on any cameras that don't have replaceable backup batteries, but I can't understand how a reasonable person would call those cameras useless. Undesirable, ok, that I can understand. Useless? No, that position basically sounds like a petulant, impractical whine. Do you really believe that?