Hate
For me, I think it's a combination of two things. One being of ego and the other being a mind game. Where ego comes into play is, through tradition, males are supposed to be big bad and tough, where nothing phases us. If we end up getting cut, scraped, bruised, or any other kind of physical injury, we're pretty much programmed into shrugging it off and continuing on. However, if you're ticklish, you might be able to withstand and hold it back, but eventually you're going to break because you can't shut off that part of you like you can with pain. It's also a matter of control. Imagine yourself being a marionette. The thought that someone knows what gets to you and how to push your buttons and the fact that they can control you emotionally and there's nothing that can be done to prevent it, such as if someone makes a nasty comment towards you, you can choose not to give that person the satisfaction by reacting to what they said. However, that doesn't work when you are being tickled.
How it can mess with your mind is if the tickler teases and taunts you by referring to it as a "weakness", "torture", or by just simply forcing you to admit that you like them doing it to you. And even though you may actually love it, you hate to admit it because to do so goes back to what I said about being a guy; you're being controlled as to what to say, how to feel, and what to think.
Love
I think somewhere in my psyche, I associate laughter with happiness and having fun. I have a tendency to be inhibited, uptight, tense, and even depressed. So, when someone tickles me, it can also be as if they are concerned about me and care enough to try to bring me out of what is troubling me at the time, whether it be lifting my spirits, getting me to relax or open up to them and/or the simple fact that I become flattered that they are paying me some attention and there is some form of attraction they see in me.
And if you think about it, being a submissive is not about being weak or being a wimp. As a matter of fact, it takes a lot of strength, courage, and trust in order to submit to someone because you are allowing yourself to become vulnerable to that person and relying on them not to betray you in any way.