Construct 2 was first released 9 years ago, in February 2011. Back then, Flash was still a dominant technology on the web; Microsoft's latest browser was Intern...
I don't think that C3 will ever be near the greatness and CAPABILITES of plugin-modded C2. C3 switched runtime and screwed over many of the plugins developers while still working with javascript and HTML5 only. It has no tangible benefit over modded C2 at the moment.
The support is sometimes downright non-existent, for example, whole C3 playable ads fiasco. You see, the supposedly more superior C3 engine can't really work with most popular ad platforms, such as Facebook. And instead of working AROUND the issue, the response was "Well, it's Facebook fault, not ours". Yeah, well plugin-modded C2 handled the case just fine and I managed to create HTML5 In-line playable ads that work with any ad network.
Construct 3 at this point is merely a bunch of gimmicky functions wrapped in a cloud with subscription price tag slapped on it. Every time I tried to make a transition, I discovered that C3 is just too constrained and limited in its functions.
To be fair, I had the same thoughts back when original Construct wasn't a Construct Classic yet and C2 was on r60+. It's just that Construct 3 needs TONS and TONS of high-quality work and dedication to outdo the Construct 2. Not even 2 years is enough. It needs stuff like ability to control frame-rate, customizable build options, maybe experimental native iOS\Android exporters, built-in cordova plugins (well tested and maintained, like CharodiXD's) to actually make a difference. And by the way, most of the features that were stated in construct.net/en/blogs/construct-official-blog-1/construct-year-review-1502
are available in C2 for a very long time with the right plugins. Also, current C3 plugin repository is just pathetic, somehow it's much-much easier to find the right thing for C2 than C3.
Construct 3 has had absolutely tons of new features added. Take a look at the major new features, performance improvements and extra capabilities in Construct 3. C3 also has loads of third-party addons, too.