Tom,
Well, for me it's all about showing much data in a limited space like showing last 6 month trends for an item, show category allocation in a mini piechart (at a glance), win/loss for x etc. etc. (just a few examples, with the full set of Sparklines we can show a lot of different things) and many times it makes sense to have these small charts together with "linear data" shown in a standard query (multicolumn). Except for that, i try to maintain a set of styling guidelines (same style throughout app) and sure I could do a pure html "query" but would look like shite next to all other queries i.e not very good UI/UX practise which makes it a no go for me.
Implementing this thoroughly via Kendo UI is probably not a biggie for Awaresoft so hoping we are a few that can use something like this and want to chip in. If there is others than me interested in this please comment. If we are a few I can ask Vlad for a quote on this.