I think Roo has a role to play for getting apps built rapidly, and I don't think there is a down side to leaving it in your project, as long as you use it to the level that makes sense. That said, the big thorn IMO is the web tier, if you don't like the current approach. It's not bad, it's just not universal and spare enough to make it a slam-dunk to adopt for every project.
My strong preference is that the Roo team or a good open source add-on cleans up the web architecture and makes it more customizable and pluggable. Extract out the Javascript tooling into an optional setting or plugin. Make that pluggable. Add more validation support for things like the standard Spring validators - let's face it, bean validation is simple but doesn't cover all bases, sometimes you need to inject logic into a validation.
I also think jspx is not as flexible as
jsp for the every day developer. I think they really need to make either one an option. Also forcing developers to go to Tiles is a bit of a strong choice so I think having a sitemesh option makes sense (or pluggable view layers).
Grails has its place. I see a number of shops starting up projects in Grails because of the productivity gains, and because they want to stay close to Spring and
Java, but not work in Java itself all day. Sometimes they chase tails around dynamic programming issues instead (why isn't this Groovy code evaluating) but there are definite advantages for the Grails (or even Rails) developers these days.
Roo really needs a community of developers to surround it and submit add-ons, JIRA tickets, and vote on issues. We have to get off of our collective rears a bit and give it a jumpstart. I think the Roo team would embrace that, and would take our suggestions seriously. Also, the Roo project needs a decent vetting place for add-ons too, like the Grails grails.org/plugins URL. So far it's not happened, but I think it needs to.
So, to sum it up, we need to build community, press for improvements, and submit new add-ons / patches to really get it growing. No open source development platform / tool grows just because the original team works on it. It takes more than that.
Ken