Of course, it is in no way super hard to learn, it is basically just about memorizing and learning, after all, but stuff that still complicates things a bit. For a Finnish speaker, the first hurdle of English is to learn to separate female persons from male persons with she and he. Articles are the next one. Thankfully there are just four options. I still simply forget to put one in there occasionally, and also get the logic of none/definite/indefinite wrong at times, because my native language doesn't have them. But you are right, in most cases incorrect or forgotten article doesn't really interfere with understanding.
True. Though like I said, and this is why it's hard for me to decide whether I see articles as unnecessary, is that even though most of the time they don't add any information, sometimes they do clarify a meaning. There are, for example, some passages in the New Testament that are more ambiguous because Greek back then didn't have an indefinite article.
English prepositions are the trickiest one, IMO, not least because the logic -- whether something is in or on or at the table and the like -- is fairly similar to my second language, Swedish, both being Indo-European Germanic languages, but still with some differences where the logic departs to two different directions, muddying the waters further.
To me, "general" usage of prepositions isn't too bad when learning another language, e.g. the fact you say "on the table" rather than "in the table", "of the table", "with the table," etc. The hardest part about prepositions is remembering when a
verb requires it, because you not only have to remember the verb itself, but what preposition to use. For example, in English you don't look something; instead, you look
at something. Without the preposition "at" the sentence is ungrammatical (e.g. "I look the sky"). So not only do you have to remember the verb itself, you also have to remember that it requires the preposition.
This makes some sense for verbs that change meaning based on prepositions (e.g. compare "to count", which means determine the number of, versus "to count
on", which means to rely on) but verbs that
always require a preposition might as well not even have one.
Word order is also something that I as a non-native English speaker have to pay extra attention to, because word order in Finnish is more relaxed.
Joe loves woods. Woods Joe loves. Loves Joe woods. Woods loves Joe. Loves woods Joe.
Joe rakastaa metsiä. Metsiä rakastaa Joe. Rakastaa metsiä Joe. Joe metsiä rakastaa. Metsiä Joe rakastaa. Perhaps somewhat more poetic, but still perfectly correct and preserves the meaning.
I went to the park for a walk today:
Kävin tänään puistossa kävelyllä. Tänään kävin puistossa kävelyllä. Puistossa kävelyllä kävin tänään. Kävelyllä kävin puistossa tänään. No difference and the meaning doesn't get destroyed.
The downside of that is, if my understanding of Finnish is correct (and it might not be), Finnish has a complex noun case system, right? English word order might be restrictive, but it means that aside from pronouns, the nouns stay the same no matter what they're being used for. The general rule of "subject verb object" seems simpler (at least for someone trying to learn the language) than having to remember all of the different case forms.