So why does Nami have more movement speed than Sona?
Seriously what is the reasoning that Sona has 10 less movement speed than Nami? Before you say Sona 's E ability gives MS look at Nami's passive. Nami has 4 abilities that can apply FLAT scaling movement speed.
You guys might be thinking a little MS is nothing but in fact its quite important when poking. When you poke and can't get away from the retaliation it can be devastating. Especially on Sona since she melts faster than anyone after getting hit with any CC like Morg binding or hooks.