It is obvious that SharpSpring needs to have an appealing layout and ease of use - things that even SuiteCRM is lacking to some extent - to be able to persuade anyone to subscribe to their offering.
I’m not saying this to criticize anyone, but I think lack of polish and ease of use are common shortcomings among many community-driven open source projects. The huge potential is often wrapped in an unappealing package (e.g. Gnome) that is unintuitive to use and painful to install and/or maintain (think Gentoo).
While SuiteCRM is easy to install and maintain, its design is aging and requires a lot of page loads, and I can easily see the appeal of slicker, newer interfaces of proprietary software. I think everything that SharpSpring does - or any other CRM system to that matter - could be done even with current SuiteCRM and more simply (I hope) with v8 and Angular, but it requires some effort on your end. You could pay any number of developers to do the customizations, and as @Mac-Rae pointed out, you’d then be left with customizations you own and could use for an indefinite amount of time - not just for the duration of your subscription. But you’re right that straight out of the box SuiteCRM isn’t that appealing at this stage.
Just to be clear, I’m very much pro-OSS and even used Gentoo with Gnome as my sole desktop system for a few years.