Camera accessories and additions

Just been in discussion on another site about onboard microphones that fit in a camera hot/cold shoe. this particual person has a very well known make but trying to point out what it doesn’t do is like bashing ones head against a brick wall.
for those who are unfamiliar on the subject there are basically directional microphones that record sound directly in front. Then there are stereo microphone that record surround sound called omnidirectional ones. each has it purpose. However I found one that does both as to incorporates types. Trying to get him to grasp the fact is neigh impossible, so I gave up.
So should one even get an extrnl microphone that fits on the top of a camera/camcorder? yes every time, not only for sound quality but to avoid wind rumble across the built in camera ones
Choosing the right microphone is as hard as choosing the right camera ,believe it or not. The price range should be a good indication of how good the sound reproduction is. There are very small ones that are neat but oh usually reproduce very tinny sound. I know I have two I don’t use much. Then there are those that clip onto clothes called lavender microphone of which I know very little about never having owned one so pointless discussing them really.
To cut down wind noise even more one can get mufflers (cruelly called dead cats) of which there again are two types, foam or hair using which or both together depends on where one is making a video.
so how important is sound on a home made video? for me it is just as important as it helps creates the “atmosphere” of where the video is being made. there are circumstances however where the sound track has to be removed and replace with music, something I don’t like.
to me if your making a video it should include sound and vision,( yesI on occassions I have forgoton to turn on the microphone)

for any help please ask me and i will try and do my best to give a decent answer