Chemistry - Why is HCl a stronger acid than Acetic Acid?

A simpler question, would be why is water a weaker acid than $\ce{HCl}$? If we were to look at that issue, we might clear some of the mess up.

Strongly reactive compounds produce weakly reactive products.

In the case of acid base theory, chloride ion is a much weaker base than hydroxide. Why is this so? The hydroxide is much smaller, and what is referred to as 'harder'. The guts of the issue is that in order for a base to deprotonate anything it has to donate two electrons to a bonding region near a proton (and in doing such render the orbital manifest, and the bond existent). In oxygen based anions, those two electrons are more likely to be in a confined region, and hence more likely to donate to the putative $\ce{HO-H}$ bond that is forming, while $\ce{Cl^-}$, being larger has a harder time getting two electrons into the bonding space required to form a $\ce{Cl-H}$ bond. So hydroxide is a stronger base. This means that when donating a proton, it is likely to just yank it back again from whatever it just gave it up to, as compared to $\ce{Cl^-}$. $\ce{HCl}$ gives up the proton and is more likely to not recapture it.

Groovy? Back to acetate. The resonance in acetate creates some diffusion of the negative charge and makes it harder to form said $\ce{AcO-H}$ bond, and as such it is a weaker base than hydroxide. However, the smaller oxygen atoms are still better and forming bonds than $\ce{Cl^-}$ and as such it is a stronger base than chloride, and therefore its conjugate acid is less acidic.

Strong acids: weak conjugate bases. Strong bases: weak conjugate acids.