Motion plus needs some work in the games themselves. Precision is only as good as the games that use it.

Does Zelda have a chance to do it right?

Hah.  More like the Gameboy Color - an adequate way of extending the system's life while adding enough to spur on more development.  Basically, it'd have increased the lifespan of the system so that Nintendo has the time to develop a proper successor, which may be further out than most think.

I think the accessory itself is great. Wii Sports Resort is one of my favorite Wii games and  justifies having the accessory by itself. Grand Slam Tenis is another favorite of mine, and while it does not require the Motion Plus it is not near as fun without it. Red Steal 2 was also pretty enjoyable and the motion worked very well I thought. I think Nintendo just has not been making games that could benefit from extensive motion. Kirby and DKC really don't need them, Metroid doesn't need them, SMG2 was able to execute the limited motion it used fine without the motion plus. I haven't played it yet but I do feel that Wii Party should have used it, having motion based mini games seems like an obvious choice for motion plus. Although that would make it difficult to play the games that use the Wiimote sideways. But overall I can't realy think of too many games that I thought should have used motion plus but didn't. I am looking forward to getting some more use out of it with FlingSmash and Zelda though.

It didn't really change much at all unfortunately.

On the plus side, it was only a $20 attachment if purchased separately, or about $10 when purchased with a bundle. Or free if purchased with a game that was heavily discounted.

While Sports Resort, much like Wii Fit were practically all that were needed to sell their respective peripherals successfully, in retrospect, it takes a pretty biased point of view to consider Motion Plus a raging success from a game standpoint or even a gaming platform standpoint. General lack of support meant it didn't really "fix" any of the problems many had with the way the Wii Remote worked (or didn't work).

Zelda will help from a game standpoint (even though it's still only one title), but maybe the time lag between when Motion Plus became available and Zelda will be available just goes to show that producing solid, quality support of the peripheral is not something that can be half-baked in no time and = instant magic.

well, 15 million m sold at min, maybe 20 for multiplayer. I did not see them failing at this

I seriously thought there would be more support.. Unfortunately third parties kinda look towards Nintendo and whether they're supporting they're peripherals before they jump in and Nintendo's support has been no where in sight..

wasnt there two tennis games that used it also?

I haven't used my motion plus in almost 7 months.

Though not "a lot", there were many more games than mentioned in the OP that had MP support (including games where it didn't make sense not to play without MP, like the Tennis games and Tiger Woods). The OP was talking about games that are exclusively MP.

Grand Slam Tennis & Virtua Tennis

Both optional, I believe

The support so far has been a little disappointing, yes. I also don't see it changing that much.

there is also NHL Slapshot to come