Here's what use title pages for.
I put them at the front of pretty much every album, to introduce it, especially if it doesn't tell a single story (my rabbit's album opens with a page with just her name and a collage of pictures), but also at the beginning of travel albums - sometimes to summarize the trip (like the DC title page below), sometimes just to say hey, this is where we went and what the album's about, the storytelling starts on the next page (like the Hawaii title page below).
I also sort of do albums by year. Well, first I did one for 2007 to 2010, and each section for a new year had a title page summing up what happened that year, along with tickets or pictures from events either too small to scrap on their own or so big they had their own separate album elsewhere. Since I don't really do anything to celebrate New Year's, there was no specific delineation between sections without those pages. 2011 and 2012 have both had enough pages to need their own albums, but I title page those as well. 2011's title page, for example, has a big journaling area where I list major events of the year that weren't otherwise scrapbooked (death of a pet, our 30th birthdays, a hail storm and the resulting new roof work, along with my usual annual tally of pages scrapped), and also features a sample of the new shingling we had put on our house, a picture of the two of us from my mom's 70th birthday party, and the tickets from a movie we went to (along with the story behind why we went).
I like title pages because they let you know what you'll be looking at as soon as you open the album. Not all albums have covers that allow you to customize them heavily, and it pretty much never hurts to have the additional clarification, especially once you have a lot of albums.
In answer to whether you need one - of course you don't. There are no rules, you don't NEED to do anything. If you feel that you would like to, feel free to do so, but if you don't feel that your albums need title pages or if you don't feel that you want to do them, then don't.