I also prefer my music to favor the higher frequencies a bit. My preference stems from constantly listening to car audio that lacked the ability to reach lower frequencies accurately, basically because "I've known no other".
Compared to my first gen Sonos Play:5 when using their truplay to adjust EQ for the space I find very similar results. The same applies to my surround sound system however the difference there is the bass in movies can be overwhelming since I live in a condo and possibly disturb neighbors.
Since getting the HomePod I've forced myself to start listening to music without favoring treble as much. And after about a week I now find the audio in my vehicles to seem "shallow". So for me it was just an adjustment from my preference to something a bit more accurate.
Preference is important though. I look at it like TV color calibration. While I have my 4k HDR tv calibrated for accuracy to the best of my ability that doesn't mean someone that PREFERS colors overly saturated is "wrong". Its just what they prefer....same applies here.
There is a host of problems with adding a native EQ adjustment. The most obvious is the difficulty (impossibility) to properly EQ an omnidirectional speaker yourself. When setting the EQ its done from the listeners position where inches matter to an audiophile/musician with a tuned sense of hearing. The reason people claim the HomePod "fills" rooms so well, has a "full" sound, and has volume consistency at range is because of the HomePod setting frequencies based on the space (aka EQ). Since the room depth (from speakers) and material can be different in all direction plus different sound frequencies respond differently to each then each tweeter is carrying different frequencies and volumes for the same "sound".
For example, I have my HP sitting on a "bar" that separates the kitchen from living area. My Amazon Echo will make a slight "echo" (literal echo) into the living room. The Echo is a volume hotspot too, to adjust it so I can hear it in my office its uncomfortably loud near it. The HP doesn't suffer from either those things, it sounds identical in the kitchen or living room and down the hall in my office I can hear sounds the Echo can't push that far (for me its the sax in M83's - Midnight city).
If I AirPlay from iTunes on my Mac I'm not completely convinced of the EQ's accuracy compared to what I set because I can't tell much of a difference walking around it (listening for peaks) however can lose the room filling sound and volume consistency. Especially increasing the highs.
I don't think its out of the realm of possibility to have a preset for "reduce bass" though, especially with the number of complaints. This is something that seems relatively easy (I could be wrong though) because I can pull the low frequencies without effecting much more than the bass, at least as far as my ears can tell.
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OP: I think you were smart returning it if it doesn't fit your needs. If Apple addresses this you can always buy another one, or get something that better fits your requirements.