Huju, yidalgu ay ahavah is said regarding am haaratzim. While the soul of prayer is the intention, the body of it is correctly saying the words. If one davens in his mind or by his own personal prayers, he has not satisfied the mitzvah of davening. If one mouths the words and merely knows the translation of the first parsha of shema and the first bracha of shemoneh esrei, he has fulfilled that mitzvah
.
Two people go to shomayim. One prayed everyday with tears in his eyes without following the siddur. The other paid lip service. We both know what the halacha would be in such a case and who would be rewarded and punished.
Hashem tells us how he wants us to serve him; it is beyond chutzpah to say what we think he “cares” about if we are minimizing a halacha. Irreligious jews say the same illogical things about tefilin, tzitzis, etc..they say “I’m a good person, isn’t that really what Hashem cares about?. do you really think Hashem cares about putting cow skin on your arms?
It’s coming from the same yatzer hora