If Outlook is so awful, how come it is still SO ubiquitous?

Very reluctantly I took a free college-branded email account from where I am about to earn my degree from so I can apply for jobs and look more legit. The downside? It runs ONLY in Outlook, which I developed a deep hatred for at my last job, since it screws itself up at the drop of a hat takes forever to refresh and update, and takes in new messages like you are downloading Lord of The Rings on a dialup modem! All these software dinks like to front like MS is the very epitome of software design and function, but how come Outlook perpetually sucks? I use Hotmail, which runs very well, yet is free and is ALSO a MS product. How does a "top shelf" product like Outlook run so terribly while a something they offer for free runs like a top?