am i missing something?
Yes. You are missing something huge.
You see, you are assuming that all beats in a bar are equal. (2/x has two beats in a bar, 3/x has three beats in a bar and 4/x has 4 beats in a bar, x being the note value that corresponds to one beat). If all beats were equal, then you would be quite correct. But they are not.
In 2/4, the first beat is strong and the second bead is weak.
In 3/4 the first beat is strong and the next two are weak.
In 4/4 the first beat is strong, the second is weak, the third is strong, but not as strong as the first, and the third is weak.
Just try to clap a waltz and you will naturally accent the first clap (hence Oom –pah – pah). Try to dance a waltz like Oom-pah-Oom-pah-Oom-pah and you will not be able to. This of course would be 2/4, or “march” time. Again, if you ever were in the army, and tried to march to 3/4 it would be impossible.
A very good way to develop awareness to beat pattern is to try to figure out the time signature of pieces by listening to them on CD, and later checking on the score if you’ve got it right.
Start with the simple times: 2/4, ¾ and 4/4.
Then try compound time: 6/8 (=2/4 – try to figure out the maths!), 9/8 (= 3/4) and 12/8 (=4/4)
Finally try the weird modern ones: 5/4, 7/4 and so on (anything goes, really).
By the way, this has little to do with the bar lines themselves. As quasimodo said, they are put in the score to facilitate reading. What really matters is the pattern of strong and weak beats.
Best wishes,
Bernhard.