The eligibility standards (where there's been no expansion) are not any higher than the old standards; they are expressed in a different way (gross versus net).
In the past, Medicaid and CHIP eligibility used a combination of an income eligibility standard--often expressed as a percentage of the Federal Poverty Level (FPL)--and a series of deductions (known as "disregards" that were like footnotes or 'below the line' adjustments to income and were determined by each state. The new way of calculating eligibility based on MAGI translates that two-part process into a one step process using an income standard that incorporates the 'below the line' deductions. This makes the new standard appear higher than the old one (e.g. from 185% of the FPL to 193% of the FPL for pregnant women). In effect, however, the new income standard represents what the state's old two-step process would have resulted in, just expressed in a different way.