Why are Slavs so concerned about all things "Slavic?"
Not sure about other "things Slavic", but when it comes to Slavic history, the main reasons are, for example:
1) Slavic origins lie in the dark - i.e. no written sources about the earliest phase of Slavs
2) In the past Slavic history was mostly written by Non-Slavic (Western European) historians
3) Those Western European historians usually depreciated all things Slavic as much as they could
And 4) Slavic-speakers are the most numerous ethno-linguistic group in Europe: any explanations how and why?
Not once have I ever heard a Spaniard talk of a brother "Latin." The French don't give a flying crap apart from their own language. The Germans left this ideology dead and buried in the 40's. The English surely don't think of themselves some part of greater Germanic brotherhood.
I agree - they are not concerned about Romance. Germanic or Celtic languages. But they are usually concerned about Western Europe.
Basically they are "Westerners" and "the West", and they talk about it all the time. This also includes former colonies (i.e. Australia is "Western").
So this is really not much different than what Slavic people do. It just happenes so that Eastern Europe is Slavic-dominated (with just minor Baltic and Finno-Ugric speaking groups), while Western is equally divided into Romance-speakers and Germanic-speakers. Greece stands out as its own thing.
Plus you have people who embrace their Celtic heritage (the French, the Spanish, many of the British), even though they speak Romance/Germanic.
Indeed much of Western Europe used to be dominated by Celtic languages before Latin took over in the south and Germanic in the north.
Not once have I ever heard a Spaniard talk of a brother "Latin."
But "we are all Westerners from Portugal to Sweden" is quite common - isn't it ??? No difference, just a bit more language families.
I would argue that "Pan-Westernism" ideology is still more alive than "Pan-Slavism" ideology has ever been.
"Western" Europe is often being defined as a single cultural unit (even though it's really not), just like "Eastern a.k.a. Slavic" Europe.
==================================
"Pan-Westernism" is arguably even much more hilarious than Pan-Slavism has ever been.
For example, you started including
Japan (!) as one of "Western"
(!) countries, once it surpassed a certain threshold of GDP per capita.
But Portugal has not been excluded from the "Western club" when it went down economically.
In the USA they have
"Western Civ. history course", which includes Egypt
(!), Mesopotamia
(!) and Greece
(!), but excludes Slavs.
