If audiences learn that Kree blood does weird things to humans, then if Coulson comes back in, say, Phase 4, and alludes to the Kree as the reason he’s alive, it will be much easier for audiences to accept that or accept anything else the MCU may want to do with Kree blood in the future.
Chances are, a good number of people who watch the Marvel movies don’t also watch Agents of S.H.I.E.L.D., which means those people may or may not have any knowledge about Agent Coulson coming back to life — unless they casually read up on stuff they aren’t watching.
What’s intriguing to note is that, by placing Coulson in such a Kree-heavy movie, Marvel could be sneakily creating a shortcut to get him to back on the big screen without actually addressing the events of Agents of S.H.I.E.L.D. in detail.