Removing data on plugin deletion is a difficult decision for developers, Jeff. If we are talking about a massive amount of data, removing it makes a difference to performance. If we are talking about a small amount of data, particularly complex settings which you would likely want back, removing data is extremely user unfriendly.

There should probably be an extra option next to the Delete button on the plugins page or as an interstitial checkbox option when you use the Delete button "Would you like to keep or remove Happy Forms data?" Perhaps even a second checkbox "Would you like to keep or remove Happy Forms settings?"

I know Core WordPress team argue options complicate WordPress but hey we're talking about professional software. There have to be options as there are decisions to be made which vary from plugin to plugin and user to user. If a decision must be made, the data and settings should be left in place for the user to remove at his/her own leisure/discretion.