Well Dedicated IP is not required, you can host your websites on shared IP without a problem, if web hosting provider is good they will keep their IP address clean...but dedicated IP is recommended for a bunch of reasons. First, there are many users who still use older OS and browsers that do not support SSL SNI and since today most webmaster use https protocol, a site on dedicated IP will work even without SNI support. In Asia win xp and older mobile OS still, share significant % of the market so... Second, you don't depend on other webmaster when it comes to IP reputation, and it is important in SEO..e-mail...etc Third, your can access to your website without domain and sometimes it is usefull but also you need to set IP to URL redirection in production since IP can be indexed as any url. Fourth, some application and scripts require dedicated IP so you have much wider range of options...also it is good for business identity...also the web server should do some extra work, parsing the user’s request to the correct website on shared IP but this is web hosting provider concern not your, and it has no big impact on performance
SSL does not imply dedicated IP - this is just something some hosting companies added. For example, THCServers.com offers cheap web hosting with a free SSL included - even if you do not have a dedicated IP. Dedicated IPs are very useful if you use the email function a lot - as you will be the only one using that address, as opposed to a shared IP where it can get blacklisted because of some users who send unsolicited emails. Best of luck!