In most languages that have auxiliary or modal verbs, the verbs usually have a number of traits that set them apart from other verbs, including often that they cannot be conjugated or accompanied by other modals or modifiers. So in standard English, you can’t say “might could” although you certainly can in some dialects (this is also true of Chinese auxiliary verbs). In Chinese, you can’t pair an intensifier with an auxiliary, so you can’t say “he really should”. You can do that in English, however.

French and Spanish seem to be somewhat unusual in that they don’t have a separate class of modal verbs; they’re just normal verbs that are used modally but there’s little that sets them apart from other verbs.

To add to the above answer English verbs tend to be much simpler when it comes to conjugating than other languages. We have just one or two endings for most verbs whether present tense or past.

For instance take the verb want, I want, he wants, we want, they want, I wanted, he wanted, we wanted, they wanted. In the present tense you just add an s or not. In the form of the past tense I presented the suffix is the same no matter who you are referring to. In Spanish it would be yo quiero, él quiere, nosotros queremos, ellos quieren. The past tense is yo quería, él quería, nosotros queríamos, ellos querían. They even have a way to say wanted if it was more recent. Like if you are at the dinner table and someone wanted you to pass the potatoes you could say él quiso las papas. English is so much easier when it comes to verbs.

English has much fewer words to learn than many languages to be able to communicate in a proficient way. Spelling is a different story.

I agree that English, with less conjugation than most other languages, is sufficiently expressive, but there are some constructions involving auxiliary verbs that seem awkward, like saying I should have instead of having a past tense form of should, and also saying I will be able instead of having a future tense form for can.