Your paper might appear on Arxiv or ECCC, be widely read and even well cited. But don't think that it is in any way "published".Suresh responded
Question is, isn't the point of publication to be "widely read and well cited"?So what is the point of publication? Certainly you want your paper easily read and cited. But also you want a careful peer review leading to a polished version that has the stamp of approval by appearing in some respectable conference or journal. Publishing also acts as a filter, allowing the reader to get some idea of the level of quality of the paper before reading it. Almost any paper can appear on an archive site but it takes more to be published.
Nevertheless if you get major kudos for your archive paper, why bother taking it further? Even if people like your paper now, it may be forgotten years from now. Complain as you will about journal publishers, they are scanning in all the old articles to make them available in a digital age. Papers that years ago appeared as old department technical reports may be lost forever. Nobody can predict what form research papers may take one hundred or even ten years from now. One day those PDF files may no longer be readable. Get your paper really published and you have a much better chance of it surviving far into the future.
A few years ago, the IEEE saw no reason to scan in old FOCS proceedings thinking that any of the important old papers appeared in better form in some journal. We knew though that if these papers weren't put in digital form, many of them might disappear forever. With some strong pushing by Paul Beame, Bob Sloan and others, those papers are now available on both the IEEE and Computer Society digital libraries.
I wanted to read a copy of Karp's NP-completeness paper which only appeared in the proceedings of a one-shot workshop in 1972. I ended up going to the library to dig it up. But library books get lost and many young people today don't even know where the library is. Later I found out Luca had scanned the paper for a course he taught. But how long will Luca's Berkeley pages last and what about all the papers that don't lead to Turing awards.
So publish your papers, best in a journal as well as a conference. Even if you don't think it matters for you in the short run, it can make a big difference for the community long into the future. What good is pushing the boundaries of science if those boundaries get snapped back because work gets lost.