Varispeed might be old hat to a tape whirring round but in the digital domain it's a fairly new thing.
I benefit from Varispeed using tools that are capable of it and there are many benefits, tuning an instrument that is in a different tuning isn't anything I've used it for though. Pitch shifting can be easily done in stuff like Audacity with reasonable success for example which is available for free.
Where 'varispeed' comes into it's own for me is when I want to record a phrase which I'm not capable of playing at the required tempo so I can record it slower and then increase the tempo to fit. Also it's useful for the disassembly of a complicated part when you just want to hear something at the right pitch but at a slower speed. Also frankly there are times when I've got a take down but realise the actual song could be improved by nudging it a few BPM either way, no problem all the audio and midi stay in sync. Being able to make subtle tempo changes between verses and choruses also becomes possible.
True varispeed in a digital DAW is not an insignificant thing to include as it either involves developing your own technology to do it or licensing stuff that already exists both avenues are not without relatively large costs. There are tools that already do the job well, I use them daily so really to warrant that cost there must be an adequate return on the investment of incorporating it.
So who wants it in Sonar?
I kinda get the frustration around the excuses and workarounds though, there's at least one workaround provided here by someone that wouldn't dream of following his own recipe when he has other more effective options available to him. That kind of irks me too, it kind of smacks of keeping folk ignorant to the fact there are some really good solutions out there already.
It's that old, old thing though there's never been one DAW that does it all, they all have strengths and weaknesses and it's still a case of marrying them up to get the best working relationship you can.