Get weird. Very often the best ideas come from an unexpected direction and there are few things more frustrating than a conservative brainstorm. If you’re unafraid of pushing things it gives the people around you permission to take some risks. Yes, you need to take in account real-world issues like timeline and budget but if you want to get somewhere faster you need to open your stride. You can always scale back an idea that's too big but it'll take you longer to get where you're going if you're taking tiny, little, baby steps.
You'll get some rejection but it's better to get a reaction than to be ignored. Years ago, when I was a political cartoonist, I received my first piece of hate mail and I was so bummed I sat down with my editor to talk about it. I felt like I'd failed. Patiently he explained that hate mail was a measure of success. My cartoon prompted someone to take time out of their day to articulate their opinion and my job was, in essence, generating dialog. It was a valuable lesson. Take a stand, be specific and give people something to react to. You won't please everyone and your work will suffer if you try.
There are tons of reasons we give ourselves to be conservative and an equal number of reasons to embrace the big ideas or convert obstacles into positive constraints. Look for the opportunity hidden in every obstacle or excuse. We don't have much money. Fine, that's an opportunity to focus your costly feature set. We don't have time to think about new ideas. Okay, but if you're struggling to make the existing idea work maybe reevaluating will save you time in the long run. I don't want to look stupid. Fair enough, qualify your suggestion with something like, "This may not fit within the timeline but maybe it'll lead to other ideas..." or "here's a crazy idea..."
The big, bold ideas will lead to better ideas so, go ahead, release the Kraken.