The use of a single word for love will likely lead to a lack of discernment. A quote from the following study on colour illustrates the point.
ProgressInColour.pdf (213.1 KB)
A series of cross-cultural studies of adult colour categorization have found consistent differences in a range of perceptual and memory tasks, systematically linked to the colour categories in each culture (Davidoff, Davies & Roberson 1999; Roberson, Davies & Davidoff 2000). Most recently, Roberson, Davidoff, Davies & Shapiro (2005) have shown that, even though two coding systems may appear to be superficially very similar, speakers of the two languages encode, remember and discriminate colour stimuli in different ways. Himba, a language spoken by a semi-nomadic, cattle-herding people in South West Africa, shows similarity in its number of linguistic categories for colour to Berinmo, the Papua New Guinean language previously studied by Roberson et al. (2000). Both languages have five basic colour categories, according to the criteria of Kay et al. (1991). However, Himba participants showed categorical perception only for their own linguistic categories and not for either the supposed universal categories, as occurring in English, or to those of the Berinmo language.
This shows that our choice of words affects our perceptions.
The paper goes on to say:
The tendency to group by similarity is pervasive, both across cultures and across cognitive
domains. Colour cognition is no exception to this and no culture / language has yet been reported that violates this principle by grouping together two areas of colour space (for example, yellow and blue) in a category that excludes the intermediate area (for example, green).1
It is plausible that, over time, a culture’s language drifts such that the classification of the colours spectrum also shifts. Given the evidence, this would mean that the perceptions of colour within that culture will shift over time as well. If boundaries between colours widen or narrow, a corresponding shift in perception will result.
I would say that the same pattern also applies to condensing multiple words such as kāma, pema and mettā into the single word of love. Doing so merges three distinct categories in the emotional spectrum In Pali (kāma, pema and mettā) into one continuous category in English (love). This would in time lead to confusion, the inability to distinguish between the original three and a general lack of discernment. Given the evidence at hand, using the word love as a translation for mettā seems like a bad idea.