I'd agree with you if it were a case of literally taking the source code from someone else's creative algorithm and copying it. So in the same way people find it offensive to copy someone else's fish shooting concept it would be offensive to straight copy the RSA algorithm and claim it as your own.

But it seems like 99% of software patent issues are about two people sitting down to solve the same common problem and independently writing their own algorithms that achieve a similar solution.

A case of people simultaneously converging on the optimum solution to a problem and implementing that solution themselves seems like a complete non-issue and what progress looks like to me but that's what most the current fuss seems to be about.