You're not going to get into too many fights if you contend that most of the ads we have to endure are pretty stinky.
Just about every ad looks like something you've seen before, sounds like something you've heard before, or smells like something you've done before.
There are a whole lot of theories about why this is so. Most of them center around the unwillingness of agencies or clients to take risks. This is true. But I think there are even bigger reasons.
1. Making good ads isn't all that easy. The reason most songs, books, paintings, and movies are crappy is that making good ones is really freakin' hard. It's the same with advertising. Most ads stink because making good ones is a bitch. My experience is that very few creative people set out to make stupid, annoying ads. They just mostly turn out that way.
2. Clients have no authority. It used to be that there was a client person who was responsible for the agency relationship and had the authority to approve advertising. It seems to me that this authority no longer exists (is this your experience? I'd love to know.) As the titles have grown grander, the authority has grown weaker. When it come to advertising, most of these guys are nothing more than coordinators who bicycle the ads around to the real decision makers to get them approved. It is possible to sell an unusual idea to one person -- it's impossible to sell it to 20. Particularly when a surrogate on wheels is doing the selling.
3. Consumers don't care. One of the harsh realities of life on Earth that I still haven't gotten used to is that most people don't really give a shit about advertising. Simon Veksner (Scamp) wrote a piece recently about how real people view advertising so differently from us. The stuff we like they don't get. And the stuff they like requires farts and talking animals. If we had consumer demand for intelligent advertising, we'd be able to force our clients to do it. But when the demand is for more farts and talking animals...hey, hey, wait a minute...I have an idea...what about a chipmunk that can sing out of his ass...