It's a tribute to Clark Gregg's popularity. Remember, the audience that reads the comics is in the tens of thousands at best, while the audience that watches the movies is in the tens of millions. The movies and shows may crib ideas freely from the comics, but ultimately the decisions they're making are driven by the needs of the onscreen productions. Gregg was a breakout star of the MCU and they spun him off to a series-regular role, as has been done with other popular supporting characters in other franchises -- Rhoda, Lou Grant, Gomer Pyle, Chief O'Brien, Rodney McKay, Captain Jack Harkness, etc. And yes, they had to bring him back to life to do it, but resurrecting dead characters due to their popularity is another trope that transcends comics (e.g. Angel and Darla on Buffy -- with the spinoff trope coming into play there too). If you mean the Cinematic Universe, I hope you're right. Where the comics universe is concerned, though, that ship's long since sailed. Character death has become merely a headline-grabbing gimmick that only sticks for a year or two before its inevitable reversal.