"X-mote" doesn't worry Nintendo for number of reasons:
1. Before "X-mote" would come out, 360 would be halfways of its life, which would limit its success.
2. Nintendo already has the "brand" in a control method in question.
3. Copying would just prove even more Nintendos strategy correct, and use in large scale would just make 360->Wii porting easier (number of smaller innovative companies still doesn't have the cash to go HD, but would save money for the big ones and what would M$ say for their gamers, they go for "casuals" or that "hardcore" can enjoy the controls too?).
4. Nintendo have prepared for others to copy its controller.
As what it comes to balance board, it's a peripheral, but not the "idea" in the console, and it was released just a bit over a year after Wiis release, so it can have "early" developer support. What M$ should have done, is copy Balance Board, not Wii Remote.
As what it comes to M$ buing companies, it really doesn't work that way, since the market M$ had previously worked in, is generally a market where it's the only big boy around and consuming the small ones isn't a problem. Now, if they would suddenly start aquiring a lot of companies, the stock price could plummet and suddenly, M$ could be just a part of Google. There are certain risks, if investors lose their interest.
Ei Kiinasti.
Eikä Japanisti.
Vaan pannaan jalalla koreasti.
Nintendo games sell only on Nintendo system.
