You mention that Rails being the dominant web framework is a strength and in the same sentence remark about how with other languages there are multiple competing frameworks. How, exactly, does this negatively impact developers? On the flip side, how does a merger between Rails and Merb positively impact developers? Developers who don't like Rails had an alternative in Merb and vice versa. How is the elimination of a choice a good thing?
The way I see it, competition here is only a good thing. Why would anyone want Rails to be the only option-- or even the de facto standard-- when it's been shown to be exactly the wrong tool for the job in several high profile scenarios? Don't get me wrong-- I'm not bashing Rails. I'm just saying it's a good thing to have a few more tools in the toolbox. When your only tool is a hammer everything starts looking like nails.