Usage of word 到 in 我很高兴见到你
Verbs like 见、买、吃、看、听 are all just express an action, when you want to express the result of the verb, you have to add “到”.  You will understand it better from the following  examples:


A blind man can do the action “ 看”, but he will never 看到 anything.
People can go to the train station 买 train tickets during Chinese new year, but it’s very hard to 买到 a ticket. 
In this sentence “我很高兴见到你” , there is a result of the action 见， the result is 你, so you can’t omit 到.