The smell from vaping is not comparable and it goes away quick, at least if you are not using some fancy liquid. Even if it doesn't, it's no worse than the smell of kebab which people are allowed to eat indoors.
Vaping indoors for any length of time leaves a sticky residue over everything - perhaps either nicotine or propylene glycol residue. Even ignoring the air quality issues for people who didn't sign up for it, it's not completely impact free.
Maybe kebab also creates poor air quality and sticky residues, but in my experience people don't tend to eat kebabs continuously every 5 minutes through the day.
I'm all for e-cigarettes as an almost-certainly-better alternative to real cigarettes (banning vaping but not smoking is ludicrous to me) - but allowing using them indoors does have a real impact on everyone else. Perhaps some are discreet, but the cloud chasing guys ruin it.