Hello,
Firstly, let me begin by saying that I completely understand your concern. I am not an employee of Epic Games but just wanted to point out that although they generously released “500+” free animations, a majority of these animations are nothing more than adjustments to about 10-15 mainsteam locomotion animations that are already on the market from various sources for free.
Motion Matching makes use of multiple many motion variances related to what we call Run or Walk but in different positions, angles, leans, etc…
The reality is of those 500 animations, you can argue that perhaps 15 to 20 of them are actually most used and you could do just fine with them without motion matching. Its not like they released 500+ animations of coveted animations such as Combat, or Dancing, or an Emotes kit, etc…
Trust me, you and companies like you, are the first people I go-to when I need really professional and accurate and robust animations and you will never get that for free anywhere!
Take care and best of luck to you.