Not sure about this. Sometimes it is even hard to tell in advance whether it is plugin or core related. Also code wise the core / plugins are not 100% separated. Meaning sometimes core accesses a plugin directly etc which is bad. Also the term core is a bit confusing since developers would understand everything below /core but here in the Team we usually consider /plugins + /core as "core". @mattab We need to change the wording that we use for /plugins and /core. Otherwise it will be always confusing, I noticed this a few times.

We could use a new plugin label for features that we would like to solve in a new plugin. Maybe this is what you meant? One downside is that we often have to add new features to core to be able to solve something in a new plugin. So we should use it maybe only when we are certain that it can be already solved in a plugin. It could be nice to have this label beside the Easy pick label.

core things are normally harder

Or are you maybe interested in a separation of issues into easy and hard? We already have an easy-pick but this one contains usually only very easy ones.

Easy/hard is also no bad thing...i wrote not a few plugins and know a bit about core/internal of Piwik, but not that deep always.

So as a contributor i think its a lot easier to write a simple plugin for a missing feature. There is good developer documentation to get started.

So if u can filter issues which can be solved with a plugin its good to get started? Also maybe to get new ideas for plugins...

Good point! We sometimes do have the case that things could and should be resolved in plugins. Created a new label: c: New plugin.
FYI @mattab