Well on the contrary, I am not so sure the term passe comes to mind ... Different situations call for different approaches, you got to be versatile in this game, there is no fire sure remedy for each and every client or project.
We have an e-Commerce client who want to target both the UK and Irish markets with immediate effect, and after a lot of consideration ,and due to their nature of business, we and they decided to go with two e-Commerce stores to two separate domains (.ie & .co.uk).
In all senses of purpose, they are the same websites, well selling the exact same products. Same site structure, same CSS, same JS etc etc.
The approach we took was to vary the product descriptions, have different URLS for the same product on both sites, have different image names and alt tags on both sites ... create different topics about the product categories on both websites, and lastly for the onsite optimisation ,we created two separate blogs on both websites with totally unique content (no cross over for the blogs).
Off page ,we started two separate social campaigns along with two separate online marketing campaigns supported by two separate ad words campaigns.
Granted there was more work involved than creating one website and target two countries, but with regards to budget for the client, it was relatively similar doing it the way we did it.
So the results ,well its rare it happens but we where pretty happy with the results so far 3 months down the line, both sites are fully indexed and ranking well in the SERP for their respective countries ...
The major key-terms we need both to rank for last week broke into the top 50 in the UK and is 11 in Ireland (really high competitive term), but this is to be expected regardless of how we ran the campaign, but the LTK and less competitive terms are already ranking first page already ...
We have been totally able to optimize each website for its respective country, from link building through to dynamic content
So does it work, yes, is it worth it ,well that depends on your business and clients situation, is it more expensive, well that depends on how your look at your budget, or your clients.
But one thing I can say for sure, would we have achieved the success we have for the client so far had we one website targeting two separate counties, not on your Nelly would we have, no way by 3 months into the campaign.
Just thought bit of perspective from someone going through the situation live might help
Regards
John