Why is loudness compensation missing from "mid-fi"?

Very often I like to listen at low volume when writing or trying to fall asleep. Without adjusting loudness, a lot of my favorite records sound faint and hollow. My current setup lacks loudness compensation, so I simply fiddle with the tone controls, but it's a crude "solution" and a bit of a nuisance. I've been researching my next upgrade, and I find it strange that some entry level equipment has loudness compensation (e.g. Yamaha A-S301), as does some high end equipment (e.g. Accuphase), but usually nothing in between. (e.g. Yamaha A-S1100). Why is that?

Every time I'm about to pull the trigger on an A-S1100 I talk myself out of it by telling myself I'll still wish I had the Accuphase for loudness compensation. It's annoying, because my setup really doesn't warrant an Accuphase — or maybe it does, if I can't find what I want elsewhere?
All of the Luxman integrateds have this. Love it for the reasons you've described.

Yamaha had (past tense, can't find it now) the best kind of loudness adjustment, continously variable. So you'd turn up the volume to the balance you liked, then turn the loudness DOWN, supressing the midrange.  Little complicated, but like the Denon version of old, works.

Get a Schiit Loki...inexpensive, clean, clear, unobtrusive in all ways, doesn't make itself known when bypassed, and by raising the levels on the treble and bass sides you immediately accomplish what a loudness control does. Put it in a tape loop or between a preamp and amp. Highly recommended.
Many mid-fi integrated amps actually have the opposite .... they have a “DIRECT” button . This bypasses bass, treble, and balance functions when the switch is depressed. This affects all inputs, and will generally give a small improvement in sound quality.

Whatever you feel is lacking also suggests a synergy mismatch between the existing upstream components and the speakers. 
Low level listening is always subject to the Fletcher-Munson contours, and that's certainly NOT remedied by bypassing tone controls. It's not a synergy issue at all...it's a perceived tonal issue relative to low level sound. Note I rarely use my Loki EQ unless some recording seems to really need some adjustment...still rare.
+1 @wolf_garcia
The alternative to Wolf's point is to get a pair of speakers for late night listening, and another for full volume.  Just what I need, another pair of speakers.... :D :D
Wolf_garcia, this is exactly what I use my Loki for. It’s on a processor loop from my preamp. I rarely use it as an EQ except for "loudness" needs later at night and/or low level listening. Works like a charm!
The loudness contour as they use to call it was used to correct the low sensitivity of the ear when listening at low levels. Some had compensation for low and high frequencies, others just low frequencies. This switch irritated many salesmen back in the day, saying too many people abused it instead of using it for what is was designed for. I believe the Mid-fi Outlaw receiver has this compensation. Good product from what I have heard. $800 retail, Stereophile class B component.