Appeal to Novelty

Arguing that one thing is automatically better in every way than another because it is newer. See New and Improved.

This argument is often made with regard to technology, where it is often supposed that anything "high tech" is automatically better than anything "low tech." Technology is all about fulfilling requirements, however, not just about cross-board improvement; for example, while a modern tank is faster and has a much more powerful gun than a World War 1 tank, it has inferior obstacle crossing abilities because its design represents a trade-off between visibility and obstacle crossing. C. S. Lewis called this fallacy "chronological snobbery".

This fallacy is the polar opposite of Appeal to Tradition.

Also called

Appeal to Youth.
Chronological Snobbery

Examples of Appeal to Novelty include:

Advertising

One ad for a home pregnancy test uses this fallacy when it says "ClearBlue Easy is the most advanced piece of technology you'll ever ... pee on." The whole ad makes it rather clear that it's being done at least somewhat tongue-in-cheek, though.
Multi-blade razors also rely on this fallacy. If two blades are good, three blades must be better, and five plus a moisturizing strip better yet. See also Shaving Is Science.
A car ad that mentioned that the vehicle in question gathered a lot of data about the road surface. And then said absolutely nothing about what it uses the data for.
An ad for a cell phone company that depicted James Earl Jones asking, "Talk talk talk pay, or pay talk talk talk?" He never explained why you would prefer the latter.
Infomercials rely on this fallcy. "The old way" of cleaning/exercising/brushing your teeth (which is usually a Strawman to begin with) is represented by black and white footage of people Too Incompetent to Operate a Blanket, while the new way is backed by dubious science, claims of cutting-edge technology, and being in color.
Whenever a new iteration of an electronic device comes out, be it cell phone, media player, gaming console, TV or whatever, you're guaranteed at least one company or line talking about the "new technical innovations" of their product; they of course conveniently don't point out that either those "innovations" have been standard for everyone but them for several years, or that the changes have little or nothing to do with the effectiveness of the product (i.e. a "new and improved grip" for a product that has to be set down to be used.)

Live-Action TV

British Television Quiz QI is extremely guilty of this trope. The entire premise of the show is turning "popular" knowledge on its head or proving old preconceptions wrong. As a result, lots of people believe the alternative, not for the inherent value of the statement, but because it's different..
How I Met Your Mother: Barney believes that new things are always better. Ted then buys ten year old scotch and makes Barney buy the newest scotch in the bar.

Real Life

The dot-com bubble was caused by many investors believing this fallacy; the new technology often blinded them to the unfeasability of many dotcom startups' business plans. Similar market bubbles have been associated with other new technology industries, including railroads, automobiles, radios and transistors.
- And tulips, yes, tulips. When tulips were first imported to the Dutch during the Dutch Golden Age, there was a massive craze for the new flowers. Prices for rare bulbs rose to (relative) heights that would make any dot.com millionaire seem like a pauper. The ensuing financial havoc after the bubble popped was devastating.