There's some Technology Marches On as it relates to any sort of TV series, be it live-action or animated. TV shows are certainly cheaper and easier to store on DVD. VHS tapes were thick and had moving parts, plus sometimes only had an episode or two on them apiece (remember, you would have to fast-forward to the episode you wanted!). Buying a series on VHS would run you well over $100 back in the 1990's, and often fill up a shelf, if you could by a complete series at all. DVDs are cheaper to produce, less prone to mechanical failure, and a whole season can fit in a thin box.
Many DVDs and Blu-rays include an "extended version" of popular movies, allowing you to get something more out of a movie you already watched in the theaters/TV. It helps that extended movies that are adaptations of books are usually more faithful to the original than the theatrical version, since some parts have to be cut out to keep the length at ~2 hours.
Thanks to the Media Watchdogs, most movies are "PG" on TV (at least in terms of language, some other stuff gets by), so if you're not a fan of censorship, the DVD version is your friend.
The shorter runs of British shows makes blowing through an entire season, er, series in one sitting a much less daunting proposition than with American shows. This is why British shows were much more likely to turn up on home video in the VHS era on both sides of the pond than American shows.
Comedy is a genre that is often better to watch in the comfort of your own home. First off, since many comedies focus on dialogue and characters instead of things like special effects, there's not a whole lot to be gained from watching them on a massive screen with surround-sound. Also, when watching a comedy on DVD, you can sit with friends, joke and laugh as loud and long as you want without risking annoying other theatergoers.
Series that are Better on DVD can become even better on Internet streaming services such as Netflix, Hulu, and Amazon Instant Video. For a monthly fee equal to or less than the price of a single season on DVD, one can get unlimited access to countless series in their entirety. The downside is the license to stream the shows can expire and sometimes may not be renewed, which essentially makes DVD the only legal way to watch certain shows.
As a general phenomenon, many fans of arc-based webcomics will wait until a storyline is finished so they can absorb it in one sitting, such as an Archive Binge, instead of having to wait for each individual comic to come out. This is especially helpful to fans if the comic is not known for its timely updating or simply has very long arcs. Many web artists realize this, which is why they tend to put continuity references in links below the comic rather than in the comic itself, so those archive binges don't become "Previously On..." every 20 seconds.