Not sure if it is a dishonest issue with the manufacturer, Toyota
Your comment is welcome !

quick conclusion: We pay for the premium audio, we deserve it

The detailed story is as followed:

Firstly, the dissatisfied sound quality with the premium audio for the 5th gen. has been a well-know issue. The main problem is on the dash tweeter and the crossover associated with it.

Secondly, I happen to own a 2011 4runner without premium audio and a 2017 4runner with premium audio. Also have a friend owns 2011 4runner with premium audio. The dissatisfied sound quality for 2011 non-premium audio and 2017 premium audio are very similar, however the 2011 premium audio is much better. It makes me wonder

I checked the part numbers for 2017 premium audio tweeter, both are 86160-47070 with msrp $109.40 . In toyota website, it is listed as "Without jbl audio. 2014-19, without premium audio. 2010-13, without premium audio". I guess this explains why we got the horrible sound quality. The part number for the tweeter with premium audio package should be 86150-35120 with msrp $249.29 based the website.

Unfortunately, the 2011 4runner without premium audio was sold when I bought the 2017 one and the friend who owns 2011 4runner with premium audio is not that close for me to disassembly his dash. Please check your part number for these 2 models if you happen to own and do not mind. Please share the info. with us, thanks!

Lastly, Is there anything we can do to ask Toyota to fix the problem?

All 4runners have the same speakers if they do not have JBL. Premium is simply referring to the headunit which has navigation and a few other functions, but the same 8 speakers as non premium. JBL puts 15 speakers in the same 8 locations.

No, not quite true, my friend's 2011 premium sounds much better than my 2017 premium.

please check the following link

Inst Panel Speaker - Toyota (86160-47070) | Toyota Parts

Description:
Without jbl audio. 2014-19, without premium audio. 2010-13, without premium audio.

Tweeter - Toyota (86150-35120) | Toyota Parts

Description:
2014-19, with premium audio

I never understood Factory upgraded audio. Anything the aftermarket offers is most likely a big upgrade for less price. Some vehicles will hide an Oem amp somewhere making future upgrades more expensive/time consuming.

Replaced my subwoofer with a kicker shallow mount and kicker powersports amp. The JBL amp in the rear and other speakers are just fine. The tweeters are not the same as the non JBL ones. Aftermarket radio with Maestro interface.

I guess you will be surprised how good the head unit and the rest of speaker are if you just replace the dash tweeters and the associated crossover with a decent ones.