I think M+ is great and helpful. Raiding has its place in challenge in a different way. M+ is something you can take as seriously as mythic raiding or as casually as you want but without lock out mechanics. I will say this though, I wish with new seasons of M+ they also released new loot into the 5 mans. In a lot of ways you can see that trinket in the first season of an expansion and quickly realize that yes.. I will have to grind for that... every seasons.