With the passage of time, the trend of developing compact system camera lenses with smaller front elements seems to be gaining momentum, although not with all manufacturers.
Panasonic originally introduced its G mirrorless interchangeable lens cameras back in 2008 and at that time, there were only two zoom lenses available. These lenses were Lumix G 45-200 mm f/4-5.6 tele zoom lens and Lumix G 14-145 mm f/3.5-5.6.
The first one of these lenses is still in production while the later one has been replaced by better and cheaper version, Lumix G 14-42 mm f/3.5-5.6 in 2010. While the aperture remained same in the new lens, the front lens element was considerably smaller. Panasonic then announced two more zoom lenses in 2011, Lumix X 45-175 mm f/4-5.6 and Lumix X 14-42 mm f/3.5-5.6. Once again, the aperture of the lenses remained when compared to earlier versions but the front lens elements shrank.
This depicts the trend of manufacturing smaller lenses with the passage of time while not compromising on the aperture of the lens. The trend does not seem to be very useful for photographers, but that is what is happening. Interestingly, this fact is not considered technically important enough to be discussed in the reviews.
A noteworthy point about the lenses is that they do not have the same maximum aperture, even though the end points remain same. However, in the middle of the zoom ranges of the newer lenses, the maximum apertures happen to be smaller. Other than that, the apertures are more or less than same at the start and end points of the focal length ranges. The distinguishing feature of the newer lenses is that inside the minimum and maximum range, the maximum aperture is smaller. But apparently this fact is not considered important enough to be revealed during the announcements for new lenses.
A downside of using this traditional zoom end point aperture is that the newer lenses turn out to be slower than the previous ones, although the overall picture quality is indeed better than the previous ones. Maybe this is the reason why this fact is not revealed during the announcements and reviews. But there are other manufacturers, such as Olympus, who seem to be following a rather different strategy. Some of the premium lenses of Olympus have considerably slower zoom end points. These lenses include Olympus M.ZD 12-50mm f/3.5-6.3 and the Olympus M.ZD 70-300mm f/4.8-6.7. So basically Olympus has been achieving the same results with a different strategy.
The difference in the maximum apertures, however, is quite small and is usually not more than a single stop. Due to this reason, it really does not have a significant practical impact, which explains the reason why it is usually not discussed in the reviews and during announcements. If some compromise is made on the aperture, while affording good performance at higher ISO ranges, it seems quite an acceptable approach. Due to the better handling of higher ISO and other factors, newer lenses do deliver better performance compared to the previous ones.