Horrible excuse.
"Online lags and will be slower, so we'll make the entire game slower!".
Funny how many other fighting games have managed just fine with a laggy online yet still be among the fastest games in fighting game history, like the Guilty Gear XX-series.
Are you saying they made the game slower for those who cannot handle the transition between Online Lag and Offline without Online lag? Because said transistion still has to be made, the game still lags online, even with the best of connections. There will always be lag when you play online no matter how much slower you make the game because information still has to go both ways before something can happen.
No, I very much doubt the game is as slow as it is because of Online. Because that would be stupid. Unless, of course, Sakurai & Co thought this was a good solution and gimped the game in terms of speed due to this kind of illogical thinking.
Games do not have to be slow because online will lag and make them slower, anyway. They do not. It's not like they care about Competitive online. No ranking lists, gimped down technical game and learning curve, they just want to make a game that as many gamers as possible will enjoy (i.e., a game for the casual market).
I doubt the casual market at large would go "Noes! The game is slower when I play online! My life as I know it is over because I can no longer do these technical combos I can do offline!".
To reiterate:
I've said it before and I'll say it again: This is one stupid reason to slow the game down. "Online will lag and be 'slower', so let's make the entire game slower!". Why? Because even if the game is slower, online will still lag and be friggin' slower!.
Let's take a look:
Let's say Game X has all shorthops come out after 8 frames. Game Y has them come out after 4 frames. Both games lag the same amount (10 frames).
Game Y will still have shorthops come out 10 frames after they are inputted! Even if the game is only half the speed of Game X, since the lag is the same, there's a 10 frame lag between an input and the inputted command occuring onscreen (first, your controller and Wii has to acknowledge the input, then it has to send said input to the server, telling it you just did something. The server then simoultaneously sends out the command for both you and your opponent's/opponents' Wiis to have the command come out at the exact same frame.
This is why online gaming lags. A lot of information has to be exchanged before even the simplest of commands can take effect. No matter how much slower you make a game, unless you change the way the game handles online, you will still lag!
FPS:es manage to largely negate lag because they handle online in an entirely different way than fighting games... a way which I assume cannot be used for fighting games.
So, let's reiterate again:
This is a stupid, illogical and downright just-so-wrong-I-wanna-hurl reason to slow the entire game down. It still lags the same. If they wanted to not have lag screw people over, they would've invested time and money into trying to minimize it.
My personal belief is that they made the game slower and more intuitive just to make it easier for new players to play. And if they slowed it down because of online, then refer to the above paragraph.