I think there's a lot of confusion going on here.
1) The ideal shiftpoint is the RPM value where changing to the next gear will deliver more torque than the current gear does. This RPM value is different from gear to gear (shifting 1st to 2nd has a different ideal shiftpoint than 4th to 5th) and throttle position (though you're generally only interested in the WOT shiftpoints).
2) The ideal shiftpoint cannot be felt, heard, seen or otherwise humanly measured while driving the car. It needs to be externally calculated or measured from dyno charts.
3) Once you have calculated the ideal shift point(s), you can either set up a shiftlight to light up at the correct RPM value (or nearly correct RPM value, if it doesn't differentiate by gear), or you learn the value(s) and shift by looking at the RPM gauge or by knowing the engine pitch at the ideal-shiftpoint-RPM. This is what "shifting by ear" refers to and has nothing to do with figuring out the ideal shiftpoint per sé.
4) Hitting the ideal shift point accurately is generally grossly overrated and not terribly important for good laptimes at all, as Tristan has nicely pointed out.
5) The big deal about the LFS shiftlight is that it doesn't light up at a pre-set (and possibly inaccurate) RPM value, but dynamically performs the ideal shiftpoint calculation in realtime, even depending on throttle position. When the LFS shiftlight lights up, then that is the de-facto ideal shiftpoint. Not earlier, not later. It is not a simple redline warning.
I don't know if such systems exist in real life, but if they do, they're probably only used in top-level racing. Maybe nobody actually bothers though, since as per point #4 hitting the ideal shiftpoint isn't as important anyway, especially if you factor in human reaction time on top of that.
Point #5 is also why not having dyno charts available was until now (or still is?) not a big deal. Dyno charts help figuring out the ideal shiftpoint - why bother with that when LFS already does the work for you?
So in summary, the shiftlight being gone is a concern because it told us the ideal shiftpoint, but it is not a big concern because the ideal shiftpoint isn't that important anyway.
Besides that, currently you can still use the automatic gearshift help to figure out the ideal shiftpoint RPM value. Yes, the automatic gearshift in LFS always shifts at the ideal shiftpoint. This behaviour is of course less than ideal, because in some situations you don't want to shift at the so called "ideal" shiftpoint.
Hope that sums everything up.