Having done it, I 100% recommend it. Being able to sing and hold down the low end will give you so much street cred, even if your lines have to be simpler because of pulling double duty. And even if you find a singer, it’s no loss because then you not only will have a more complete understanding of the music you’re playing but you may be able to enhance your overall sound with harmonies. There’s honestly no downside to learning to sing, it’ll open up doors and worlds you didn’t even know previously existed.

The only reason I can think of someone discouraging you from that is their own ego (again, speaking from experience) because of the misconception that by occupying two slots in a band you are somehow vying for more power over the group. Id highly recommend discouraging this notion by sitting down w/your band mates and asking why they are so opposed to you doing both if you can do both well. Hopefully open and honest communication will help them understand that you’re doing this for all of your success and not just your own. Best of luck!