I guess search engines think about anchor text as it would be an "off page title tag", a label in the linking architecture. So i think removing the needless words can increase the relative weight of the desired keyphrase hereby improve the rankings for those expressions.

Of course links can be a way to bring traffic to our sites through clicks, so branding can be also important.

We are dealing with a couple of issues here, but I will try to explain them in simple terms.

1. density
2. prominence
3. relevance.

To make the maths easier to understand, I will make it a 4 word search phrase

Temis blue widget sales where the term being optimised for is widget sales

1. density = 4 words divided / by 2 as the phrase we are working on makes up 50% of the anchor text

2. Prominence = our search phrase is at the end of the anchor text, and as such scores lower in fact it scores 50 & 25 = 75 Rather than 100 & 75 = 175 if they were the first words there. so in this regard it counts for LESS than 50%

3. Relevance = again this scores down, as we have only 50% relevance to the target phrase, with Temis & Blue being irrelevant. This means you would need twice the volume of links to get the same benefit for that phrase.

It is important though to understand that the figures above are STRAIGHT CALCULATIONS and NOT how google uses them. I have left them as simple as this so there is a direct correlation between the numbers of 4 words, and the outcome figures 25% etc.