I think your quotes from the Monster Manual are quite relevant. I'm trying to answer based only on the the book itself.
Darkvision is only mentioned among the "Senses" of the different lycanthrope types for Weretigers and Wererats, and it is not mentioned at the general description of the lychantropes. (The closest we get is the mentioning that their eyes might glow red in the dark, which seems unsufficient evidence.)
However, the Monster Manual defines "Special Traits" in general as follows (page 10):
Special traits (which appear after a monster's challenge rating but before any actions or reactions) are characteristics that are likely to be relevant in a combat encounter and that require some explanation.
Every lycanthrope subtype in the MM (ie. Werebear, Wereboar, Wererat, Weretiger and Werewolf) shares the "Shapechanger" special trait. The general formula of this trait is:
The were[type] can use its action to polymorph into a [Size modifier/-][type]-humanoid hybrid or into a [Size modifier/-][type], or back into its true form, which is humanoid.
Now, from the possible non-humanoid and non-hybrid results of the polymorph action, the Wererat's Giant rat form is the only one that has a 60 ft dark vision (see MM. page 327.). This fact is also emphasized on the Wererat statblock: it gets 60 ft. of darkvision in rat form only (page 209).
A humanoid who gets the Wererat subtype of the lycanthropy curse may use their action to polymorph into a Giant rat, thus gaining it's darkvision capabilities.
Since "Senses" is indeed not mentioned among the features a PC gains as a lychantrope (unlike, say, damage immunities), my RAW interpretation suggests that the Weretigers' darkvision is not inherited.
If it is used for player characters as well, the "nonhuman lycanthropes" variant rule on the 206. page of the MM may provide an alternative scenario. If a player character already had darkvision before gaining the curse, they may "retain one or more of its humanoid racial feat"; already existing darkvision may be such a trait.