Muhammad ibn Abd al-Wahhab was pretty straight forward. He believed in a strict code of monotheism and wanted people to behave as the saxaba did and live by a strict code sourced from the Qur'an and reliable Xadiths. He made efforts to eliminate shirk-y practices that had taken root among Peninsular Arabs like sacred trees, Djinn reverence, building as well as visiting shrines made for "saints" and yada yada. Wanted to cleanse Islam down to its bare and
true parts and get rid of the organically morphing of religions that happens over the centuries. He also wanted to gradually settle the majority Badu population as they were the ones most taken to shirk type practices and borderline irreligious behavior:
source: IBN SAUD: The Desert Warrior Who Created the Kingdom of Saudi Arabia
Now, if one disagrees with his vision that's one thing but I don't think he was at all some sort of evil, malicious or dishonest character. He believed what he believed and believed it with conviction and, yes, he was willing to be brutal to enact his beliefs and you can condemn him for that if you wish but I never got the impression he was some conniving character. Just a guy discontent with the disorder and chaos of Arabia back then and he felt that a more strict adherence to the tenants of Islam could save them and restore order, peace and unity.