Federal regulators found themselves under the spotlight Monday as the massive Biotechnology Industry Organization’s annual convention opened in Boston. As more than 15,000 life-sciences professionals converged on the Boston Convention and Exhibition Center for four days of panels and networking, a Food and Drug Administration plan to make decisions on new drugs more transparent and consistent drew criticism. Drug makers have long complained about what they consider a needlessly complicated review process. But an FDA-proposed framework did little to quiet concerns.