I partially disagree, you don't need very fast internet connection to run full node. Fast internet connection only needed to let your node download whole blockchain quickly.
Yes....but, you do waiting weeks to do the initial download will turn off a lot of people.
Also, add reliable internet. If your connection keeps dropping and you have to keep waiting to get caught up to send your funds or to look for payments also sucks.
That's why i use word "partially".
In my opinion people running a full node on RPis aren't really helping anyone. They are more of a hobby thing to use rather than a serious full node set out to make a contribution to the backbone of bitcoin.
Although it's hobby thing, i think they still help Bitcoin network if they allow incoming connection (with proper router configuration).