Keep in mind that this is tantamount to eliminating the word “me” and replacing it with “I”, using it for both subject and object form.
Which is actually happening to a certain extent in the opposite
direction. People are so used to saying So-and-so and I
that when they want to say something like Tom saw me and Bill
at the park they can't do it, so they say the
"ungrammatical" Tom saw Bill and I at the park. You can do
this now in almost any context and no one will even notice except
prescriptivist grammar curmudgeons.
When young children try to regularize irregular words (like saying “gooder” instead of “better”, or saying “Me want ice cream,” instead of “I want ice cream,"), we correct them, repeatedly and they learn the “right” word form for each usage. Apparently, parents of many current adults didn’t do that consistently with who/whom, so the difference hasn’t cemented itself into the vocabulary of many people, such as yourself.
That's not what happens. For the most part, children are not
taught language by their parents. They ACQUIRE language: their
brains are wired to connect up to the language patterns they hear
around them. If children don't acquire the who/whom rule,
it's mostly because the people around them aren't using the rule.
English speakers have NEVER been particularly good at distinguishing between who and whom. People have been breaking the rule as long as the rule has existed. And it's not just because who and whom are less common than I and me. English pronouns have changed a HUGE amount over the centuries. The complex system of pronouns used in Old English shows this. There used to be dual first- and second-person pronouns. Most pronouns used to have separate accusative (direct object) and dative (indirect object) forms. Who, what, and which as interrogative pronouns used to have instrumental cases. There used to be another interrogative pronoun that meant which of two? Relative pronouns (who, that, which) used to be different from interrogative pronouns (who, what, which). There used to be separate classes of indefinite pronouns (anybody, everybody, everything, anything) and negative pronouns (nobody, nothing) that had their own declinations. All of this is lost now. Not because parents forgot to teach their children about them, but because people change the way they speak the language, even within a single generation, and over time the changes add up.
There's an interesting anecdote in a Stephen Pinker book in which
he describes a child saying gooder to her parent and the
parent saying gooder back to the child. The child stops
and says the parent is saying it wrong; that's the way I
talk, not you. Language acquisition is so much more than just
learning rules.
Note that preserving this difference between “me” and “I” is completely arbitrary.
It's not arbitrary. Language change happens for reasons, and
those reasons are complex, but they're not arbitrary.
Many languages, like American Sign Language and Klingon, don’t distinguish between subject and object forms of pronouns. There are other cues as to whether the pronoun is a subject or an object besides the form of the word. In English, having the form of the pronouns different is one of the many areas of redundancy in the grammar, requiring one more element of agreement, making the language one notch more complicated to learn, giving people one more area to make grammatical mistakes that are wholly unnecessary.
The fact that so many languages include agreement, which you
consider redundancy, suggests that there's a purpose to it, that
it's not arbitrary at all. One good reason for agreement is that
people are not digital computers. When you're listening to
language, you're not necessarily processing and analyzing every
single sound you hear. It's not that precise a process. Redundancy
helps reinforce an expression. It's much easier to process *I am
happy* than *me happy.* While *me happy* contains only the
information I need, it's easier to mishear the sentence as *he
happy* or *we happy* or *she happy* or even *Bea happy.* There is
much less chance of such mistakes with *I am happy,* as you have
two separate cues as to the person being described. (This is a
simplistic example, and not the only reason for grammatical
redundancies like agreement.)
-- SuStel http://trimboli.name