by not fully reading and understanding these agreements, am I in violation of these terms and the agreement?
No. A contract is an exchange of considerations (aka benefits). The sole act of reading the terms of an agreement gives no benefit to the counterparty, whence reading and understanding them is not part of the actual contract. Consequently, not reading or not understanding the contract cannot constitute a violation thereof.
The relevance of reading and understanding the terms of a contract pertains to proving the formation of a contract, and more specifically the contract-law tenet that agreements be entered knowingly and willfully. Thus, your signal of having read and understood the contract (for instance, by clicking on a checkbox) serves as your counterparty's evidence of your full awareness of what the contract between you two entails.
am I ethically in the wrong?
In most cases, no, you would not be ethically in the wrong. The fact that generally speaking it is not unethical does not render your question "off topic", though.
(I am sorry for some users' arrogant habit of suppressing parts of others' posts. Unfortunately some people pretend that ethics has nothing to do with law. If it were off-topic in law, ethics as a keyword would not yield the thousands of results when searching court opinions, nor would there be an entry therefor in legal dictionaries such as Black's Law Dictionary.)
As explained above, your manifestation of having read the agreement serves a purely evidentiary purpose as to formation of a contract. That evidence might be brought up in the event that either party attempts to void the contract or that the counterparty goes after you for breach of contract.
Falsely purporting your awareness of the terms of a contract might lead to legal problems only in very few, unusual scenarios involving mental states such as negligence. Even if the false portrayal does not amount to breach of contract or a violation of laws, a court might rule in equity when the party's omission and misrepresentations thereof causes injuries to a party to the contract or to third parties.