Yes, you absolutely should
Your boys are trying to share something valuable and important with you. I doubt you'd be this worried about it if it wasn't digital - what would you do if they wanted to build lego with you? Or draw, or paint? This is the same thing. They want you involved in their activities.
I view screen time as more of a necessary evil than anything else. My boys get 30 minutes each per day, and I would be happier if it were less.
So where's the harm in sharing that screen time with them?
The interactions we have are not very high quality: occasionally sharing resources, sometimes planning together.
You may get more out of it by bringing a more focused attitude to the game. When I multi with my two boys, I tend to do most of the building and working with the game mechanics - I construct a house, a farm, storage, crafting areas, etc, which the boys can then use when needed. It helps keep them more focused in a single area, and helps to inspire them to build their own creations.
I'm concerned about communicating that interacting over video games is quality human interaction.
Both of my boys have their own COWs (Computers On Wheels), so when we multi in Minecraft we bring all our computers together into the same room and we can talk to one another directly. The game then becomes an activity we're all enjoying together, rather than the medium of our interaction.
So, this is basically a conflict between my understanding of what's best for my kids, and what they enjoy. How should I approach this? Should my priority be to push for my values, to do something that seems to be meaningful to them, or find some middle ground?
So I go back to my original point - this is an activity they want to share with you. I doubt you'd be this conflicted if they wanted to build with Lego with you, or draw, or play a sport. If you insist on only pushing your values, you discourage independence of thinking or action, and teach your kids that what's important to them doesn't matter to their parents.
Plus, Minecraft is awesomely good fun.