collectd comes packaged by default in a bunch of distributions and telegraf does not -- for basic functionality telegraf doesn't really buy anything and takes more configuration.
Not everything uses or even can run ubuntu. I have a similar setup and have a number of openwrt devices that also feed things into grafana via collectd - so I already have that up and running.
What kind of packaging does openwrt use? We publish tarballs of Telegraf that should work, but if there's a different packaging format that would make it easier to install we can look into adding that.
