I wouldn't say it's not popular, many British expats live there and also not a few Americans. Maybe not as popular as Spain, Portugal or France but it's more popular than Central and Eastern European countries like the Czech Republic, Slovakia, Hungary, Poland, Slovenia, Croatia to name a few. And I'd pick either of those over Germany as they offer more in terms of food, many of them are a tad friendlier and some even have better climates to boot.

As to the drawbacks - the main ones are Germany has mostly a bad climate, mostly unfriendly locals, too many rules, too few freedoms, the culture is a bit boring, and to top it all it has a very difficult language and a nation too proud to speak English. Most of its main cities are in boring, flat as a pancake areas. If Danish pronunciation is ignored German is probably the hardest Germanic language of all. The grammar alone is nuts and then you get a mile long compound nouns when a sentence could've done better. It sucks for dyslexic people as many of us can't parse long compound nouns easily.

Nature is beautiful but mostly in the places that border France, Switzerland, the Czech Republic, Austria or the sea/Denmark anyway so if you're going to spend years learning German why not go to Austria or Switzerland instead? Switzerland salaries are higher with lower tax. Austria has a small job market but most cities are cleaner. The nature in both is even more beautiful and more easily accessible even from the big cities. Munich isn't that close to the Alps, compared to Austrian and Swiss cities. Berlin is in the boring Northern European plane, just some lakes around, so why not go to the similarly flat but surrounded by the sea Denmark instead where you're never far away from beautiful beaches?

I would like to add that many towns and cities in Germany aren't exactly beautiful. Ulm and Regensburg sure are very beautiful, but those are sleepy towns with few jobs, even fewer for expats. Augsburg was beautiful but looked a bit dirty for a city of that size in a developed Northern European country. I bet its Polish and Austrian equivalents are spotless in comparison. Dresden is beautiful but too sleepy for a city of that size, feels like a nursing home on weekends compared to Bratislava. Heck, the smaller Salzburg felt livelier than Dresden.

Berlin, Frankfurt, and even Hamburg and Munich aren't exactly cities I'd call beautiful. Their French, Austrian, Swiss, Czech, Danish, Dutch etc. equivalents for sure have more interesting architecture and beauty. It's a culture that has contributed a lot to literature, art, they've made some very nice cars and came up with one of the best dog breeds - GSD. <3 But as an actual place for living it feels too boring, cold and more like being in a work camp than a place where you can enjoy life. A work camp that isn't very clean ironically. I was shocked at the lack of cleanness of their train stations and DB delays when I'm used to Dutch trains. The Netherlands, Denmark and Austria make Germany look like their poor cousins. And even Slovak and Hungarian trains are more punctual. Seeing a Western country with Balkan-like train punctuality was shocking!