I don't care which event is the most relevant as long as I get news of the games I'm looking forward to.

As others have already stated, you have to consider the position Sony is in ATM.

The PlayStation 5 is right around the corner and most, if not all, of Sony's 1st Party development has shifted towards that system. And the games they all have in development for the system aren't going to be remotely ready by 2019. Furthermore, the PS5 itself will likely be a 2020 release and most importantly of all, the PS4 is still selling excellent numbers every week, at $299 and $349 respectively, and still has plenty of fuel left in the tank. An announcement and reveal at E3 2019 would be a shot in the foot for PS4 momentum. When you have a system that is as successful and selling on the level that the PS4 is, it would be very foolish to do something that could effect sales considerably. At least wait until 2020, when the PS4 has started to show its age, starts noticeably losing steam, and has had a price drop or two down to $199-$249 to try and keep sales going.

Speaking of the PS4, the fact that they are bailing on E3 most likely means that whatever PS4 games that are in development fall into one of three categories: 1) Games we already know about (Death Stranding, Ghosts of Tsushima, Shenmue 3, Last of Us II). 2) 3rd party games we know for a fact will be there (Insert Yearly CoD/FIFA/NBA/Madden game here). 3) Unannounced 1st or 3rd party games that probably aren't that big to justify an E3 reveal and are better suited for some other event Sony will be part of (PSX, TGS) or just get its own announcement at a later time.

And let's be honest, Sony's E3 this year was rather lackluster. If they had decided to go through with this year with the information and details listed above, it probably would have sucked again. So, why bother?
Have patience, plan ahead, and wait until just the right time to play the cards on your hand.
Once most of the games we know about are released in 2019, they'll be back again at E3 2020 with a vengeance.