They certainly tried, and I personally looked at the MSP430 launchpad as a fun distraction last spring
Another big hit was the chips they released initially--the 1st gen "value line" chips were hideously underpowered, like 2KB flash/128 bytes of SRAM, more ATTiny-like in size. The current "v1.5" LaunchPad you buy comes with 3rd-gen value line parts, up to 16KB flash, still not quite arduino but doing a lot better (and with hardware UART).
I hope the Stellaris LaunchPad catches on quicker, it looks like OpenOCD is starting to work with it so I have high hopes a UNIX-based environment can be easily deployed for Stellaris development soon. What I am personally more impressed with is the LaunchPad's BoosterPack form factor ( http://processors.wiki.ti.com/index.php/BYOB )--they have thought of a simple and straightforward way to expand the capabilities, while retaining (in theory) some backwards compatibility with boosterpacks made for the MSP430 for example. Much nicer than Arduino's "shield" layout IMO.