Non-emphatic letter-spacing changes are susceptible to automation, thus should be automated.
If, for instance, uppercase text requires wider spacing, the browser — or better still, the font renderer — should work that out; the designer should not have to explicitly tell it things like that.
Since, in any case, most manual typography is already algorithmic (if such-and-such condition, the spacing needs to be increased), and since the 'judgement calls' about the aesthetics of type are already encoded into the font by the foundry, manual typography outside the foundry is /obsolete/: machines can do it better, because they can use optimisation algorithms to find the best trade-offs (compare, for instance, TeX's line-breaking algorithm to the common manual approach of "first-fit, but backtrack if the solution is too poor").
If, for instance, uppercase text requires wider spacing, the browser — or better still, the font renderer — should work that out; the designer should not have to explicitly tell it things like that.
Since, in any case, most manual typography is already algorithmic (if such-and-such condition, the spacing needs to be increased), and since the 'judgement calls' about the aesthetics of type are already encoded into the font by the foundry, manual typography outside the foundry is /obsolete/: machines can do it better, because they can use optimisation algorithms to find the best trade-offs (compare, for instance, TeX's line-breaking algorithm to the common manual approach of "first-fit, but backtrack if the solution is too poor").