No, it won't negate the advantages of 2FA, even if it reduces it a little. Security is only effective if it does not makes the user resort to workarounds, otherwise they won't use the security option. I would not use a 2FA token if it took 5 minutes to arrive, for example.
In this case, remembering the device for a while will not force the user to enter the 2FA token on every request, and will protect the user if his password leaks somehow. An attacker exploiting this perceived weakness would have to compromise the device itself.
And if you value your security, please don't use "token by SMS", "token by phonecall" or anything that uses your phone number to send the token. SIM swap attacks are real, and lots of people are losing access to their accounts because of it.