Is it illeagle to print a check and not use a magnetic ink for the account and routing numbers?

For legal questions - you should consult an attorney.

For other reasons, not to be mentioned, most bankers are not going to discuss this issue for security reasons.

And practically speaking, if the bank isn't able to process your checks w/o the magnetic ink, then they won't be able to service your account. They will have no choice but to close the account, and they don't need a legal reason to do that.

Talk to your bank; their check printer probably has check stock available which is suitable for your laser printer AND for the bank's check sorting machinery. (The stock will have your account number preprinted in magnetic ink, just like the ordinary checks you're used to, but it will come in sheets that feed through the printer.)

Check your bank's fee schedule. Most banks charge a substantial ($1+) for each check, if the check fails to automatically process because it was improperly printed.