Adapting the 74LS170 open-collector "register file" to active-high TTL input
The 74LS170 is not inverted from input to output even with the open collector outputs when looked at logically (i.e. input pin to output pin); the datasheet truth table shows it, but a better source is the logic diagram. 



Looking at the inputs (at the top), the inputs are inverted prior to storage (in the red ellipse) and therefore what is actually stored in the internal latches is \$ \overline D_n\$

When reading the data back out, the effective open collector inversion (in the blue ellipse) converts the stored data back to the original input.

Open collector predates tri-state outputs by some time (possibly decades) and was used primarily for bus applications (so that one of many outputs could drive a single signal line); tri-state achieves the same thing but by disconnecting the output from the signal line, but came much later and when it first showed up there was a significant price premium and it had it's own issues when used (the timing between driving nodes needs to be controlled so that we don't get bus contention; an issue that is irrelevant in open collector architectures).

That does not mean we don't have to take timing into account - we do but in open collector there won't be any damage to parts if two (or more) outputs happen to be driving the same line at the same time, so from that perspective it is much easier.

The concept of Wire-OR (or really wire-AND) was specifically designed so that we could have an effective output gate on a bus as effectively a data selector [we needed to know which output we had selected. of course] (apart from the numerous other applications it is used in).

As noted in comments on your other question(s), when the '170 came out it had designers drooling (dual port, read from one register while writing to another enabling primitive pipelining) - it really was a 'wow' part at the time.

As you note, the '670 came out quite a bit later (when tri-state was more the norm in bus architectures and had become the de-facto standard and the price had dropped).

Tri-state has advantages of course; rise and fall times are close to equal because they are actively driven for both high and low (in open collector the effective RC time constant had to be evaluated for how fast the signal line would rise back to a high).

So it is a mixture of target application and history as to which type of output is suitable.

The 74LS189 was introduced (if memory serves) around 1980, some years after the '170 (almost 10 I believe).

Open collector is also often used in window comparator circuits, incidentally.