There are great packages available that handle these items for you. the Meteor Development Group is dedicated to maintaining the sub-projects that make up Meteor and equally dedicated to supporting community packages by not stepping on too many toes. Just take the the routing snap-fu with Angular as an example of how not to do things. Meteor is focused on making a framework with as little friction as possible with their community. It is a real joy to work with it.

* There maybe no official support for reactive joins but they are very easy to make with packages like Publish-Composite: https://atmospherejs.com/reywood/publish-composite , plus you get the freedom to build your data and denormalization how you want. I think it just requires a dedicated dev to study Mongo data structures with Blaze&DDP. Some devs are just not dedicated enough to learn how to do it right.

* i18n, I cannot speak to that, never had a need yet.

* Forms are freakin' amazing in Meteor with the Autoform package: https://atmospherejs.com/aldeed/autoform

* Routing is freakin' amazing in Meteor with the Iron:Router package: https://atmospherejs.com/iron/router

* Courses, docs and resources are freakin' amazing for Meteor examples considering it's age. That said, all docs for all software could be better, it is more of a personal thing.

Just curious @alexandernst are you a .net dev because it sounds like you are not an Open Source dude? Instead of gluing awesome things together and being creative it sounds like you want a big company like Microsoft to come in and offer everything to you, tell you how to do everything, and box you into their ways. Packages do not have cooties, haha. And Meteor is built on Node. You have access to NPM as well.