Agreed too - we really need to be able to report by form submission, so for instance building a report in the custom builder that shows anyone who has ever submitted Form X [so not just first/most recent conversions], and then being able to analyze those results.
Some examples: we sometimes want to filter out particular lifecycle stages or lead statuses; plot form submissions over time or filter to just show specific date ranges; see info on which contacts have associated deals; group results on company or email domain…