But on the rare occasions I need it, I often really need it. Especially because code that has survived sufficiently unchanged for that long ofte has done so for important reasons.
The amortized value per commit for really old code is likely low, but you get them 'for free' because you want to do them to have them for recent code, and the overall value of having them for older code to the codebase as a whole can be significant.
I'd say the SVN history challenge is an excuse - firstly there are tools that can do it.
Alternatively you can easily enough keep the SVN repo around for those rare occasions people really need to dig.