This may be long, but please bear with me
To be fair with wsr it came out earlier and therefore sports champions should have had a chance to be a more improved experience since it also has a camera which helps for deph, but that doesnt mean wsr is any bad at all. (what I dont like about champions are the mainly the characters)
WSR may seem very shallow if you just give it a try. (I´ve personally spent over 50 hours on it) There are some types of stamps (I dont know how to call them) you get by beating certain objectives in each sport (that is to me one of the most rewarding things in the game at least in the single player mode and some are very hard to get). There are usually 5 stamps to get per sport.
Also, in most sports you get medals depending on how many points you´ve earned (for example getting over 2000 poinst in speed slice gets you a gold medal which you can see showing next to the points in the lower part of the screen just before you press A to start the sport)
Another thing to take into acount is that wsr is a game aimed mainly at casuals, and therefore when you start the game and are on a low level (it starts getting more difficult over the 500 points mark) the game may seem too easy and some people may think the game beats itself.
That is speacially noticeable in table tennis where if you just wagle the remote (though it tracks the wagle very well), it will automatically make the hit when the ball is near, but as I said, if you work to get 1500 plus points the waggling wont have the same effect. Also if you want and try to play it realistically you can give great spin to your game and it is very different from just wagling
On the other hand wagling does NOT work for most of the games. Speacially in the greatly improved bowling and golf games. Even though you dont have a camera to help in wsr, those two games feel just right. Ver very precise. And are the ones I´ve spent most time on. Also air sports, basketball, sword play (speed slice needs a special mention, I´d advice you to get over 2000 points on that one), archery and disc gold are pleasent surprises (at least to me). Of these, disc gold (though precise and fun) lacks in comparison to its tiger woods pga tour 10 counter part because you have the whole mii body interfering when you move the controller up whereas in pga tour 10 you just have a hand which improves the immersion (and I´d advice you to try PGA 10´s disc gold if you really want to see how precise motionplus can be).
Then there are some sports that are not so good and feel a bit awkward (though I´m sure there are people that like them) like cycling (speacially this one), canoeing (precise but boring), wakeboarding, and power cruising.
Overall it is a very good game and I think it deserves the 80 metascore so it is up to you whether you get it or not, but if you do I hope you enjoy it ;)
I think the main reason why sports champions did not beat wsr´s meta score was because it came out a bit over a year after wsr and some critics may think is wasnt anything that hadnt been done before (even though it is more precise). But champions is also a great game and definitely worth playing.
I hope I helped. and thanks for your attention :)