rifkin Speaking broadly, I know of a few companies (think along the lines of Starbucks, Top Golf, ect...) that use only Sketchup for their entire design process. I agree that not many architecture/engineering firms use Macs but Enscape has a board user base. There definitely was a large group of vocal users on here that were pushing for a Mac version, so the decision to include it isn't unreasonable. Like you mentioned though, does it justify the resources and/or the choice to include it right now? 
Also, I completely agree with your second point. BUT, like I've mentioned before in other comments, for instance, there is no native way to get a water feature to look good in Enscape. If my clients wants a home built around a fountain or cascading waterfall and also want to fly around it during a meeting, I'm forced to use another program regardless of how the rendering software integrates with the modeling software. Its features like that and ones others have posted about that are key to the "live rendering" user base but get skipped over for reasons that make people question the decision to continue with the program.