essentially no grammar change is a "simplification". every language has the same complexity in it's grammar, it mostly depends where that complexity lies

you might just be confusing complexity with big words or large tables of grammatical affixes. over time, languages tend to either get more synthetic (closer to a 1=1 correspondence between words and morphemes) or agglutinative (many more morphemes per word), and it wraps around at the end - premium synthetic languages then start tacking words together, some start making other constructions, and suddenly you're on the agglutinative side!

Maybe... but some language requires more context for one to understand the utterance or sentence in order to give the statement the proper understanding. Why do some languages have a decrease in inflective grammatical cases (where English has now 3, whereas Hungarian retains 15 or more? And some languages are in the process of losing use of some cases; however, I'm unaware of languages gaining case complexity. Pidgins are simplified languages that allow communication between unintelligible languages. I would suggest they use simplified grammars.

Pidgins are almost a completely different thing. Since by their nature, every speaker of a pidgin is a fluent native speaker of at least one other language, the pidgin doesn't have to meet all of the communication needs of all of its speakers. Once they cross over into creoles eg have native speakers, they fall into the same structures as all other languages.

context is a part of language! pragmatics is essentially context as it relates to language, and pragmatics is a part of linguistics. languages gaining case complexity largely happens by affixation of prepositions - i can't think of any examples off the top of my head but you'll have to take my word on it occurring.

One common pattern for this is the reason English has a comparatively simple grammar. English was learned in adulthood by a series of invaders (Vikings, Normans). Adults aren't very good at learning new languages so they tend to discard the harder parts. Indonesian (Bahasa) is easy to learn for similar reasons, while some of the indigenous tribal languages of Indonesia are among the most complex in the world.

There's a theory in linguistics that languages tend to complexify if they're used by a small, insular group, but tend to simplify if they're used as a trade languages. Evidence for this theory can be found in languages like English and Swahili, which are grammatically simpler than their Germanic and Bantu cousin languages. You can also see in Caucasian languages that the languages spoken by higher altitude speakers (who were more protected from the various waves of conquest in the area) being more complex than the lower altitude speakers.

the relative simplicity of English is pretty much modern, if you go back to the way it was spoken ~200 years ago, I think you'll find it a lot more complicated in terms of expressions and artistic complications, pretty close to French actually

Maybe... Spanish and Portuguese ware used in trade a lot and they don't seem to have simplified much. On the other hand, like English Danish has simplified even further, but it was never a great trade language --it may have been a language of trade in the Baltic basin many centuries ago but not in the last half dozen centuries.

> Spanish and Portuguese ware used in trade a lot and they don't seem to have simplified much.

Latin is another standard example of a language losing complexity due to being learned by large numbers of adults. Greek still has a system of noun cases. Spanish and Portuguese don't.