Online clothes shopping is one of my favorite hobbies. At night, I often relax at night by shopping online. I even for clothes & shoes my friends (although I fail miserably at accessories).
Online shopping is great for many reasons... it's quick and easy to find an endless list anything you want, including vintage items. You can shop from anywhere. Often online retailors provide free shipping for purchases & returns. Online shoppers bypass the crowds and long check-out lines at malls. Returns are much simpler online than at a store. Online items are often cheaper than those in stores. It's easier to do price comparisons and to be notified of sales. If you're not sure about a purchase (or want to wait until it's cheaper), you can add it to your "wish list" or "favorites" and decide later to purchase it. Lastly, your friends can easily send purchase suggestions to you (or you can easiy create a list of which friends can purchase items for you).
Those against online clothes shopping state 2 reasons for not doing it: 1) the inability to feel the fabric or see the quality of the item and 2) the inability to know if the item will fit and which size to purchase. However, both of these concerns are negligable nowadays. All websites provide a list of body measurements and their size equivalents and they publish customer reviews stating how customer's have found the item to fit. With free/easy shipping, a shopper can purchase 2 sizes, try both on, and send the wrong size or both items back. There is the option to try-on the item in a brick & mortar store and then order it online (because it's cheaper). After a while, online shoppers know the quality of their favorite brands and they know their size in the brand anway.
Online clothes shopping has been most quickly adopted in the UK & US (I've heard that Japan, Singapore, S. Korea, the UAE, and Saudi Arabia are close behind). This is largely because the online shopping is so price and consumer-friendly in the UK & US, compared to other countries. Items sold in the UK & US are usually cheaper than the same item sold in another country (i.e. "capitism vs. socialism" and also price-sensitive consumers). Additionally, the UK & US stores can offer sales whenever they want. Stores in other European countries can only offer sales at certain times of the year, as governed by law. The US & UK online stores tend to offer free shipping to individuals in the UK & US. While consumers in other countries have to pay for expensive shipping (even when shipping from a store within their country). The UK & US charge minimal tax on shipments from another country. Wheras other countries pay a huge tax on these if ordering from a country outside your residence.* Lastly, customer service is usually much better at the online stores in the UK & US - it's clear that they want your repeat business.
As I'll be visiting the US soon, I've spent the last months adding items to "favorites" list online, waiting for the price to drop, then ordering the item and shipping it to the US address. This allows me to get many different items of good quality at good prices. I'm looking forward to coming home and spending the first afternoon trying on items. If you haven't already tried online shopping, I highly encourage it.
*In Germany, this tax can be as high as 100% the price of the item. Because of the tax, a huge item delivery service has been established at my work. When UK & US colleagues come to Germany on a business trip, they often "volunteer" (bless them) to bring over items for us which we've ordered online and had shipped to their houses.