That just means they need to be written better. Cross-species romances are an interesting concept but I don't think BW should create too many options for them. Otherwise it makes them seem run-of-the-mill when in fact they should be seen as a very unusual (except for Asari perhaps). For instance, in ME2 it felt like you could basically wh*** your way across the galaxy, notwithstanding the odds that other species aren't necessarily going to be sexually compatible with humans.
In ME4 I would like to see no more than one romance option for each gender outside of the obligatory human and Asari romances (although that would have to change accordingly with multiple playable races). With good writing there are plenty of other ways to interact with alien species for insight without romancing them.
... Nah.
Personally, I think that yes there should be more insight into culture beyond 'Turians are militaristic humans, Asari are wise humans, Salarians are Scientific Humans' so on and so forth which is somewhat the extreme they kind of made out to be. Yes, you can do that without being in a relationship with them, but at the same time being in a relationship with a member of the particular species doesn't really... Make that more difficult.
I mean you can learn all sorts of stuff about Turians from Garrus without having to be 'involved' with him, stuff about Quarians from Tali while being Fshep, so on and so forth. As such I don't think having a romance option would be a silver bullet to remove content you could learn. It might mean that some information isn't known persnally about a character if you aren't at least friendly with them but that's your choice.
I think having LIs for either Gender of the other species is fine. You can't romance a Salarian so that's fine, you could have one Asari, that's cool. A couple Turians one for each? Or two? So on? I mean, the number of potential LIs in ME2 and ME3 were substantial enough, maybe too many in Me2 but I wouldn't say it harmed much...
Gah, rambling a bit much.
OT: Fem and MShep should have at least one gay partnet as well as the Asari (or two if the Asari is a 'lesbian' or 'straight'), one Bisexual because why not, then a couple of straight LIs. Altogether, 9-ish possible. Is nine too many? You aren't romancing them all at once and they can be functional characters on their own so if your crew is ~80% LIs but they don't have to be then you're still good.