There's a reason why video magazines give "rules" like "dont go crossing the line".

Not everyone who watches videos is a geek. Most of the audience have no idea what it's like to make or edit a film. They have learnt a film "language" and videos which go too far away from this language are difficult to understand.
Also, a lot of what you perceive is subconscious. In the case of a cut "crossing the line" nobody consciously thinks "hang on, I don't understand what happened to the visuals there" but subconsciously the brain has to process the fact that someone has changed direction in a fraction of a second. This isn't difficult but it means that:
(a) whilst processing this, a part of the plot or conversation might be overlooked. Not a problem in a music video but could be a problem in a drama.
(b) it draws attention to the fact that this isn't real life. When watching a video you have a "suspension of disbelief". In a drama/thriller/feature you get drawn into the plot, the characters become real and you empathise with the situation. A "wrong" cut reminds you that it's just a film, and the viewer partially loses this "suspension of disbelief". In a music video a "bad" cut distracts the viewer from the visuals and the music.

That's why these conventions are important. When you're new to film/videomaking there's a tendency to say "well I understand it, what's the problem?". As time goes on you stop trying to show off, you stop shouting "look at me aren't I clever" and you concentrate more on the viewer and less on yourself. This is when you realise that these conventions (I hate the word "rules") are actually very, very valid.